You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: Thank you so much. That is all I will need today. Sentence2: Great, how many tickets would you like to purchase? Sentence3: That would be perfect! Sentence4: I am looking to go from cambridge, and go on friday arriving by 14:30 Sentence5: Okay, how about the TR5901 leaving at 13:34 and arriving at 14:24 with a duration of 50 minutes? The cost is 16.50 pounds. Would that work for you? Sentence6: There are 266 trains going to Peterborough. Can you give me a departure day and time so that I can narrow down your choices? Sentence7: Your tickets are all booked, reference number R5P65TW5 Sentence8: I'd like to find a train to peterborough. Sentence9: Thank you for contacting Cambridge TownInfo centre. Have a wonderful day! Sentence10: 7 tickets please. Can I also have the reference number for the booking? Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User