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. Curtis went around, finding the officers, issuing orders. There were still some unconscious men to be revived. In a sheltered cove among Comerford Comerford's entire Comerford 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! Comerford's Curtis got a glimpse of the design on which he was working, and his lips relaxed in a faint smile. Comerford Androka had arrived on board the from Norfolk. With him came a boatload of scientific apparatus and equipment, including a number of things that looked like oxygen tanks, which were now stored in the forward hold. Androka had watched over the day before she sailed daily in the room in the superstructure that had been assigned as his laboratory. Sometimes, Curtis thought old Androka was a bit wacky—a scientist radio station on a high promontory on the north shore of the islet. Another had found the remains of tents and log cabins, recently 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. cheeks, streaking them with glistening furrows. The fellow was a headache to Curtis. He was overfriendly with a 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 oilskins, blinking his eyes against the yellow light. Curtis closed the door and nodded toward the bent form of Zukor Androka, with a quizzical grin. "Old Czech-and-Double-Czech is working Comerford Androka decrees silence over the German airways! Try it! Try it, I say!" Bob Curtis stared at him, as if questioning his sanity. Then he hastened to the radio room, with Nelson at his heels, and the Czech trotting along behind. still wearing his earphones, and stood staring upward incredulously at the aërial. "Get us a radio cross-bearing for location at once," Curtis said sharply, for the operator seemed in a daze. "Bearing, sir?" The man brought his eyes down with difficulty, as if With the coming of dawn, a little exploration revealed that the "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 As if to mock him, the ship's radio began to answer: "Station 297 calling U. S. Cruiser Comerford Comerford Comerford calling Station 297!" the operator intoned, winking at the two officers over Androka's discomfiture, and asked for the bearings. Comerford !" Curtis sighed with relief. He saw that Nelson was staring fiercely at the radio operator, as the man went on calling: "U. S. Cruiser Comerford Comerford Comerford Comerford 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 must be right. Continue as you were!" "I'm relieved, sir, just the same," Nelson admitted, "to have the radio 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. "It's a funny thing," the latter said, still dialing and grousing, "how I got that cross-bearing through and can't get another squeak out of wires were alive to the touch and set him to shaking his head at the tingle they sent through his inquiring fingers. Curtis left him at it, and went to rejoin Androka in the cabin. He "Those tanks you have below," Curtis said, "have they some connection with this radio silence?" A far-away look came into Androka's eyes. He did not seem to hear Curtis said: "I understand." "And if the Nazi agents in America knew of the islet from which my zone of silence is projected—" Androka paused, his head tilted to one side, at the end of a swing or smacked against something solid. Curtis felt Nelson's hand grip his shoulder, as he put his lips close to his ear and shouted: "You must have been right, sir, and the radio Comerford Comerford Carethusia " the other was "convoy." But gradually his eardrums Comerford gas mask. Nelson spoke in a low tone, his lips close to Bradford's ear. "It worked, Joe!" "Yeah!" Bradford agreed. "It worked—fine!" The limp bodies of the Comerford's 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!" for a career in the United States navy—and no one suspected me. No one—" "Sometimes," Bradford put in, "I think Curtis suspected you." "Maybe Curtis'll find out his suspicions were justified," Nelson said bitterly. "But it won't do Curtis any good—a commander who's lost Comerford men—officers, seamen, mechanics, radio men, technical experts, all German naval reservists living in the United States, who've been sent here secretly, a few at a time, during the past six weeks!" The three—Brandt, Nelson and Bradford—stood on the bridge and talked, while the efficient stretcher-bearers worked industriously to remove the limp bodies of the Comerford's with strange-looking radio equipment, and more gas tanks like those Androka had brought aboard the Comerford with him, and dynamos and Comerford Carethusia ?" Nelson asked, in a puzzled tone. Brandt said: "She's a freighter in a convoy out of St. Johns—twelve 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!" Comerford old-fashioned trench mortar, and which connected with cables to the room that served as Androka's laboratory and workshop. Another crew was installing radio apparatus in the mizzentop turret. Comerford's Comerford A man with a flashlight was approaching him. Its white glare shone for a moment in Curtis' face, and the familiar voice of Ensign Jack Dillon spoke: "Commander Curtis! Are you O. K., sir?" "I think so!" Curtis' heart warmed at the eager expression in Dillon's "How about yourself, Jack?" Curtis added. "A bit of a headache from the gas, but that's all. Any orders, sir?" Curtis thought for a moment. "Muster the crew, as best you can. We'll try to make a roll call. Is there any sign of the ship?" Comerford puzzle—Androka's zone of silence the bearings given by radio Navigating Officer Nelson's queer conduct. They were all part of a never trusted him. Nelson

<question>:
Who are the four to blame for the Comerford’s incident?

<options>:
A Nelson, Androka, Brandt, Bradford
B Curtis, Androka, Brandt, Bradford
C Bradford, Nelson, Androka, Curtis
D Androka, Curtis, the radioman, Bradford

<answer>:

A