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

<passage>:
THE ULTROOM ERROR sense of humor, though, even in the Ultroom! HB73782. Ultroom error. Tendal 13. Arvid 6. Kanad transfer Occasionally she glanced at her son in the play pen, who was getting his daily dose of sunshine. He was gurgling happily, examining a ball, a cheese grater and a linen baby book, all with perfunctory interest. "All right, Joe." He reached into the pen, picked up the baby. As he did so the baby's knees hit the side of the play pen and young Laughton let out a scream—half from hurt and half from sudden lack of confidence in his new handler. But this did not deter Joe. He started off with the child. Around the corner and after the man came a snarling mongrel dog, eyes bright, teeth glinting in the sunlight. The man did not turn as the dog threw himself at him, burying his teeth in his leg. Surprised, the man dropped the screaming child on the lawn and turned to the dog. Joe seemed off balance and he backed up confusedly in the face of the snapping jaws. Then he suddenly turned and walked away, the dog at his heels. "I tell you, the man said he was my brother and he made me think he When her husband did not answer, her head sank to her arms on the table and she sobbed. him. "We'll go up and look at him together." They found Reggie peacefully asleep in his crib in his room upstairs. They checked the windows and tucked in the blankets. They paused in think he was her brother. She doesn't even have a brother. Then he tried to get away with the baby." Martin leaned down and patted the dog. "It was Tiger here who scared him off." The police sergeant looked at the father, at Nancy and then at the dog. He scribbled notes in his book. The sergeant flipped his notebook closed. "You'd better keep your dog inside and around the kid as much as possible. Keep your doors and windows locked. I'll see that the prowl car keeps an eye on the house. him, making idle comment until Dr. Tompkins came down the stairs with the sleeping baby cuddled against his shoulder. "Never mind the check, now, Martin. I see we're ready to go." He went over to his assistant and took the baby. Together they walked out the front door. Stuart crumpled to the ground, the baby falling to the lawn. Dr. forward on his face. The figure of a woman ran from the house, retrieved the now squalling infant and ran back into the house. Once inside, Nancy slammed the door, gave the baby to the stunned Martin and headed for the telephone. "One of them was the same man!" she cried. guy carrying your baby, don't you think?" "I shot him in the legs. The other—the other turned and I shot him in the baby." He reached over and smoothed the sleeping Reggie's hair. Nancy, who was rocking the boy, narrowed her eyes. "I wonder why they want our baby? He's just like any other baby. We don't have any money. We couldn't pay a ransom." gurgled with delight at the change in environment. This peaceful scene was disturbed by a speeding car in which two men were riding. The car roared up the street, swerved toward the parkway, tires screaming, bounced over the curb and sidewalk, straight toward the child and mother. Reggie, attracted by the sudden noise, looked up to see the approaching vehicle. His mother stood up, set her palms against her cheeks and shrieked. The car came on, crunched over the play pen, killing the child. The said. Must have happened years ago." "That's odd. The man who accosted Mrs. Laughton in the afternoon was bitten by their dog. Later that night she said she shot the same man in the chest. Since the scars are healed it obviously couldn't be the same man. But there's a real coincidence for you. And speaking of the dogbite, the Laughton dog died that night. His menu evidently didn't agree with him. Never did figure what killed him, actually." "Any record of treatment on the man she shot?" his chest. This gave him the appearance of being alert despite reclining. Even as he lay, his mouth held a hint of a smile. Arvid 6—for John Smith was Arvid 6—had lain in that position for more than four hours, when suddenly he snapped his eyes open and appeared to be listening. For a moment a look of concern crossed his face and he swung his legs to the floor and sat there expectantly. Arvid 6 knew Tendal 13 had materialized and was somewhere in the building. Eventually there were some sounds from beyond the steel cell and doorway. There was a clang when the outer doorway was opened and Arvid 6 rose from his cot. "I'm really sorry about that," Arvid 6 said. "You didn't have to come along at all, you know," Arvid 6 said. "How well I know! How sorry I am that I ever did! It was only because I was sorry for you, because someone older and more experienced than you was needed. I volunteered. Imagine that! I volunteered! Tendal 13 reaches the height of stupidity and volunteers to help Arvid 6 go back 6,000 years to bring Kanad back, to correct a mistake Arvid 6 made!" "All right, all right," Arvid 6 said. "I'll admit I've made some mistakes. You're just not adventurous, that's all." "Shut up! For once you're going to listen to me. Our instructions child right out from under its mother's nose' were your exact words. And before I could stop you, you did. Only you forgot an important factor in the equation—the dog, Tiger. And you nursed a dogbite most These twentieth century machines aren't what they ought to be," Arvid 6 said. "You never run out of excuses, do you, Arvid? Remember what you said in the Ultroom when you pushed the lever clear over and transferred in." Tendal 13 turned and looked steadily and directly at Arvid 6. "Do you know what I think? I think you deliberately pushed the lever over as . That's how simple I think it was." Arvid 6 flushed, turned away and looked at the floor. "What crazy things have you been doing since I've been gone?" Tendal 13 asked. Arvid 6 sighed. "After what you just said I guess it wouldn't amuse you, although it has me. They got to me right after the accident before I had a chance to collect my wits, dematerialize or thousand or more or until their bones are like paper." "I just wonder how angry Kanad will be," Arvid muttered. HB92167. Ultroom Error. Tendal 13. Arvid 6. Kanad transfer out of 1951 complete. Next Kanad transfer ready. 2267. TB92167 Arvid 6 rose from the cot and the two men faced each other. "Before we leave, Arvid," Tendal 13 started to say. "I know, I know. You want me to let you handle everything." "Exactly. Is that too much to ask after all you've done?" barred door the jailer fumbled with the keys and clumsily tried several with no luck. Arvid 6, an amused set to his mouth and devilment in his eyes, watched the jailer's expression as he walked through the bars of the door. He laughed as he saw the jailer's eyes bulge. "Arvid!" Tendal 13 walked briskly through the door, snatched Arvid 6 by the shoulders and shook him. The jailer watched stupified as the two men vanished in the middle of

<question>:
What was Arvid 6's mistake?

<options>:
A Arvid 6 dematerialized in front of humans.
B Arvid 6 transferred Kanad back in time 6000 years.
C Arvid 6 crashed a car into a tree which killed a woman.
D Arvid 6 dropped the baby when the dog started barking at him.

<answer>:

B