Given the task definition and input, reply with output. You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: Thanks so much. That was all I needed today. Sentence2: Did you have a certain time you needed to leave or arrive by? Sentence3: Booking was successful. Reference number is : K5MBWIXI . Sentence4: I want to book for 5 people, 4 nights, starting from sunday. Sentence5: I would like to leave cambridge and arrive by 20:15. Sentence6: you leave at 7 and arrive by 7 51. Sentence7: The travel time is 51 minutes. As far as that hotel goes, it's a moderately-priced 4-star guesthouse on the east side. Sentence8: What is the travel time? I'm also looking for information on a hotel, carolina bed and breakfast. Sentence9: I could suggest train TR8636, which arrives by 07: 51, should I book? Sentence10: I don't need the booking yet. You've already give me the train ID. I just need the departure time and the travel time. Thanks. Sentence11: Can you help me find a train going to london kings cross leaving on thursday? Sentence12: If you need anything else, please contact us. Question: Who has spoken the sentence 6? (A) User (B) System
Answer: (A) User