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

<passage>:
Dzhackoon nodded. "For a moment, it appeared you were disinclined to "What outfit did you say you were with?" Dan asked. "The Inter-dimensional Monitor Service." "Inter-what?" the florid man at his side. He had a high, thin voice, like something that needed oiling. "Something about important information regarding safeguarding my paintings." and night—" "Two hundred and twenty-five," Kelly snapped. "—but no one at all in the vault with the paintings," Slane finished. "Of course not," Snithian shrilled. "Why should I post a man in the vault? It's under constant surveillance from the corridor outside." "The Harriman paintings were removed from a locked vault," Dan said. "There was a special seal on the door. It wasn't broken." "By the saints, he's right," Kelly exclaimed. "Maybe we ought to have a man in that vault." "Another idiotic scheme to waste my money," Snithian snapped. "I've made you responsible for security here, Kelly! Let's have no more turned in at an office and closed the door. "Now, as the old buzzard said, I'm responsible for security here. If those pictures go, my job goes with them. Your vault idea's not bad. Just how cheap would you work?" from closely guarded galleries and homes all over the world. It was obvious that no one could enter a locked vault, remove a stack of large canvases and leave, unnoticed by watchful guards—and leaving the locks undamaged. Yet the paintings were gone. Someone had been in those vaults—someone who hadn't entered in the usual way. Theory failed at that point vault—day and night—waiting—he would see for himself how they operated. He finished his sandwich, went to the shelves and pulled down one of of the filaments died, leaving only a faint illumination from the night-light over the door. When the thieves arrived, it might give him a momentary advantage if his eyes were adjusted to the dark. He groped his way to the bunk. crackling, to span the closing gap with a grate of metal, the cage Never mind. He took a deep breath, ran over the speeches he had prepared for the occasion: Greeting, visitors from the Future.... balding, the other shorter and round-faced. Neither of them noticed Dan, sitting rigid on the cot. The thin man placed a lantern on the gent's room—" "Never mind, Manny," Fiorello cut in. "It appears there's been a leak." Dan shook his head. "No leak. I simply deduced—" "Don't act hastily, Manny. You know where you'll end." Fiorello. "Listen, I figured out—" "Perhaps you were right, Manny," Fiorello said. "Complications are the cage. "What about this ginzo?" Manny jerked a thumb toward Dan. "He's on to the door open and collar the lot of you! Came up through a tunnel, did you?" aimed it at Manny. "You stay here, Manny! I'm going with Fiorello in the time machine." "Are you nuts?" Manny demanded. "I'm flattered, dear boy," Fiorello said, "but—" "You can't leave me here!" Manny spluttered, watching Dan crowd into "We'll send for you," Dan said. "Let's go, Fiorello." Fiorello's elbow caught him in the mouth. Manny staggered back "Manny!" Fiorello released his grip on Dan, lunged to aid his swallowed hard and nudged a second lever. The cage sank like an elevator into the floor, vivid blue washing up its sides. Hastily he reversed the control. Operating a time machine was tricky business. One little slip, and the Slane molecules would be squeezing in among brick and mortar particles.... way he'd planned, but after all, this was what he'd wanted—in a way. The time machine was his to command. And if he gave up now and crawled back into the vault, Kelly would gather him in and pin every art theft of the past decade on him. It couldn't be worked. So far he had only found the controls for maneuvering in the usual three dimensions, but the time switch was bound to be here "What happened to Manny and Fiorello?" to catch a brown eye upon him. Only one. The other seemed to be busily at work studying the ceiling. "I hope," the voice said, "that you ain't harboring no reactionary racial prejudices." of some interest to you. The loss of Manny and Fiorello is a serious "You mean you want me to take over operating the time machine?" "Time machine?" The brown eyes blinked alternately. "I fear some confusion exists. I don't quite dig the significance of the term." "That thing," Dan jabbed a thumb toward the cage. "The machine I came here in. You want me—" "Time machine," the voice repeated. "Some sort of chronometer, perhaps?" "Huh?" "I pride myself on my command of the local idiom, yet I confess the The beachball head leaned forward interestedly. "Clue me, Dan. What's a time machine?" "Well, it's what you use to travel through time." The brown eyes blinked in agitated alternation. "Apparently I've loused up my investigation of the local cultural background. I had no idea the wide mouth opening and closing rapidly. "And to think I've been spinning my wheels collecting primitive 2-D art!" "But—don't you have a time machine? I mean, isn't that one?" "That? That's merely a carrier. Now tell me more about your time machines. A fascinating concept! My superiors will be delighted at "But the way Manny and Fiorello came sailing in through the wall! That has to be a time machine they were riding in. Nothing else could just materialize out of thin air like that." "You seem to have a time-machine fixation, Dan," Blote said. "You shouldn't assume, just because you people have developed time travel, that everyone has. Now—" Blote's voice sank to a bass whisper—"I'll make a deal with you, Dan. You'll secure a small time machine in good condition for me. And in return—" you with a time machine?" Blote waggled a stubby forefinger at Dan. "I dislike pointing it out, Dan, but you are in a rather awkward position at the moment. Illegal with an abundance of the local medium of exchange. Equitable enough, I should say. What about it, Dan?" "Ah, let me see," Dan temporized. "Time machine. Time machine—" "Don't attempt to weasel on me, Dan," Blote rumbled ominously. "I'd better look in the phone book," Dan suggested. "Time, time. Let's see...." He brightened. "Time, Incorporated local cells. "Now, off to gather in the time machine." He took his place in the carrier, patted the seat beside him with a wide hand. "Come, Dan. Get a wiggle on." "Very well, Dan." Dan dropped the carrier through the roof, passed down through a dimly seen office. Blote twiddled a small knob. The scene around the cage grew even fainter. "Best we remain unnoticed," he explained. The cage descended steadily. Dan peered out, searching for identifying they do time...." He tugged at a lever suddenly the machine veered in the park. Perhaps it was some sort of burglar alarm. But if so, why hadn't it gone into action earlier? Dan took a deep breath. Sound or no sound, he would have to get back into the carrier and transfer it to a five, Inter-dimensional Monitor Service." "That siren," Dan said. "Was that you?"

<question>:
Why did Dan believe Manny and Fiorello were time travelers?

<options>:
A He deduced it when Blote described their job functions.
B He suspected it based on the peculiarities of their crimes.
C Mr. Snithian warned him of the possibility.
D They spoke about time travel when he was eavesdropping in the vault.

<answer>:

B