Q: You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.
Sentence1: Yes, for 6 people, and I will need the reference number please. Sentence2: There are about 70 options. Do you have a particular travel day? Sentence3: I found it, it's a cheap guesthouse in the west. Would you like me to book it for you? Sentence4: Your reservation is confirmed. Your reference number is 31S3UK6M . Can I help with anything else? Sentence5: Hi, I'm looking for a train that's going to bishops stortford from cambridge, what kinds of options are there? Sentence6: Yes for 6 people for 5 nights starting saturday. Sentence7: Thanks, I also am looking for a hotel called finches bed and breakfast a friend mentioned. Sentence8: I would like to travel on Thursday and get there before 13:30. Sentence9: No, that is everything I need. Thank you for all your help! Sentence10: I got 6 tickets for you your reference number is ADZ8DIQ2 . Sentence11: Train TR2929 leaves Cambridge at 11:29 on Thursday and arrives at Bishops Stortford at 12:07. Would you like me to book it for you? Sentence12: If there is nothing else you need help with, have a great day. Goodbye. Question: Who has spoken the sentence 4? (A) User (B) System
A:
Answer: (A) User