Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
always acted as if he had some secret, something to hide. Curtis recalled that Nelson and Androka had long conversations together—conversations which they would end abruptly when anyone else came within earshot. And Nelson had always been chummy with the worst trouble maker in the crew—Bos'n's Mate Bradford. naval organization. If you could silence all radio—silence of that sort would be deadly! to the door, paused there, and flung a backward glance at the man in the cabin with him—Zukor Androka, the elderly Czech scientist, a guest entire complement of two hundred and twenty men were present—except Navigating Officer Nelson, and Bos'n's Mate Bradford! And Zukor Androka was also missing! of the United States navy, here aboard the cruiser Curtis got a glimpse of the design on which he was working, and his lips relaxed in a faint smile. Androka had arrived on board the Comerford the day before she sailed from Norfolk. With him came a boatload of scientific apparatus and crew was marooned on an islet, about a square mile in area that they had been put ashore without food or extra clothing or equipment, including a number of things that looked like oxygen tanks, which were now stored in the forward hold. Androka had watched over equipment of any kind, and that no boats had been left for them. his treasures with the jealous care of a mother hen, and spent hours behind. Curtis was studying the wreckage of the wireless station, wondering if this might have been the source of Androka's zone of silence, when Ensign Jack Dillon came up to him. "There's a coast-guard cutter heading for the island, sir," he black-browed bos'n's mate named Joe Bradford—the worst trouble maker on board. But there was no question of his ability. He was a good navigating officer—dependable, accurate, conscientious. Nevertheless, his taut face, restless, searching eyes, and eternally nervous manner Don't let a little error get you down!" "But this storm, sir!" Nelson avoided Curtis' friendly eyes and slipped "Call up to the bridge to stop her," he told Nelson. "We can't afford to move in these waters with such a possibility of error!" Nelson complied, and the throbbing drive of the engines lessened at once. Nelson said: "I've been wondering, sir, if it wouldn't be Comerford ships or amateurs on the shorter. "Dead!" Androka muttered, with a bitter laugh. "Yet not dead, gentlemen! The set is uninjured. The waves are what have been upset. I have shattered them around your ship, just as I can eventually shatter them all over Central Europe! For the next two hours, no radio messages With the coming of dawn, a little exploration revealed that the Curtis was the first to speak. "Your secrecy might well cost the United States navy one of its best light cruisers—and us our lives!" he said angrily. "We need that check by radio at once! If you're not talking nonsense, call off your dogs till we learn just where we are!" Androka held out his palms helplessly. "I can do nothing. I have given orders to my assistant that he must keep two hours of radio silence! I can get no message to him, for our radio is dead!" from Cay 364." Commander and navigator had both scribbled verifications of the numbers. Ignoring the gibbering Androka, who was wailing his disappointment that messages had penetrated his veil of silence, they closed. The sky was again a blanket of darkness pouring sheets of rain at them. Nelson went back to the bridge, and Androka returned to the commander's cabin. Curtis lingered in the wireless room with the radio operator. tingle they sent through his inquiring fingers. Curtis left him at it, and went to rejoin Androka in the cabin. He found the little inventor pacing up and down, shaking his fists in the air of silence is projected—" Androka paused, his head tilted to one side, as if he were listening to something— On deck, there was shouting and commotion. Curtis rushed out, pulling on his slicker as he went. The shout from the watch forward had been "Breakers ahead!" He was beside Navigating Officer Nelson on the bridge, and saw the helmsman climbing the rapidly spinning wheel like a monkey as he put it hard aport. Then the ship struck. Everything movable shot ahead until it brought up to his ear and shouted: "You must have been right, sir, and the radio bearings and my reckoning wrong. We've hit that reef a terrific smack. I'm afraid we're gored!" completely at the mercy of the wind and the waves. Curtis heard the anchor let down, as if by invisible hands, the chain lowered accommodation ladder and transferred into waiting lifeboats. Nelson swore under his breath. "Reckon it'll take a couple of hours before the ship's rid of that damn gas!" got a neutralizing chemical in one of them tanks of his that'll clear everything up inside half an hour." "I'd rather get along without Androka, if we could!" Nelson muttered. "He's nothing but a crackpot!" "It was a crackpot who invented the gas we used to break up the wrongs," Nelson continued. "If America hadn't gone into the First World War, he wouldn't have lost his business my mother would still unconscious crew and row them ashore. And when that task was completed, lifeboats began to come alongside Androka had brought aboard the Comerford with him, and dynamos and Brazil—through the blockade," Nelson said, "without taking the risk of capturing a United States navy cruiser." Carethusia is taking over." "Can we trust Androka?" Nelson asked, with a sudden note of suspicion in his voice. "Yes," Brandt assured him. "Of all men—we can trust Androka!" foreigners whom it chooses as its agents," Brandt pointed out. "Androka misfires, if there is the slightest suspicion of treachery on his part, his daughter and the others will suffer. Androka's loyalty is assured!" Nelson turned to watch the forward fighting top of the Comerford Descending a companionway to see what was going on below, Nelson found that portholes were being opened, and men were spraying chemical around to rid the below-decks atmosphere of the lethal gas that had overcome the Comerford's American crew. Returning to the bridge, he found that the tide in the inlet had risen considerably, and that the cruiser was riding more easily at her anchor. Then, at Brandt's orders, the anchor was hauled in, and lifeboats and a motor launch were used as tugs to work the vessel entirely free of the sand bar. This was accomplished without difficulty. out his hand. "Congratulations, Herr Kommander Nelson!" he said. "Ve have stolen one of the United States navy's newest and fastest cruisers!" He made a There was a solemn note in Dillon's voice. "No, sir. She's been worked off the sandbar and put to sea!" The words struck Curtis with the numbing shock of a blow on some nerve center. For the first time, he realized fully the tragedy that had swept down on him. He had lost his ship—one of the United States navy's fastest and newest small light cruisers—under circumstances which smelled strongly of treachery and sabotage. As he thought back, he realized that he very purpose. The pieces of the picture fitted together like a jigsaw puzzle—Androka's zone of silence the bearings given by radio Navigating Officer Nelson's queer conduct. They were all part of a carefully laid plan! All the suspicious circumstances surrounding Nelson came flooding into never trusted him. Nelson

<question>:
Of all the characters, who is seen as an antagonist in the article?

<options>:
A Androka's assistant because he turned off the radio.
B Commander Curtis because he rarely complied with the other crew members.
C The radio man on the ship because he could not complete Commander Curtis's orders.
D Androka, because his actions severely inconvenienced the crew of the ship.

<answer>:

D