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

Sentence1: I'll be departing from Norwich on Sunday. Sentence2: Have a nice day. Sentence3: There are many trains to Cambridge. Where will you be departing from? Sentence4: Ok, there doesn't appear to be any trains leaving then. Could you leave later? Sentence5: I am looking for a train to Cambridge please. Sentence6: Yes. can you tell me the total travel time as well? Sentence7: I apologize for the earlier confusion. We have several trains that will meet your needs. TR6419 departs Norwich on Sunday at 11:16. Will that work for you? Sentence8: It is going to be 79 minutes total. Sentence9: I can leave at 10:45. Sentence10: Great, that's all I need. Goodbye! Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User