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: I have a train leaving at 9:01 on thursday. Would you like to book that? Sentence2: On what day will you be travelling? Sentence3: Yes please book that for 1 person. Sentence4: Hi. I need a train out of cambridge. Sentence5: There are several trains out of Cambridge but i need to know your destination and preferred day and time of departure. Sentence6: Booking was successful, the total fee is 75.09 GBP payable at the station. Your reference number is ZYKE5A4L . Do you need anything else? Sentence7: I will be leaving on Thursday. Sentence8: My destination is birmingham new street and I need to leave after 9:00. Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User