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 Cambridge for London Kings Cross Monday at 19:00, would you like me to book it? Sentence2: Alright. Goodbye now. Thank you! Sentence3: I can assist you. What is your destination and departure time? Sentence4: The ticket will coat 23.60 pounds and it will arrive at 19:51. Sentence5: I need the arrival time and price Sentence6: I would like to find a train that is leaving Cambridge on Monday. Sentence7: Thanks, that's all. Good bye. Sentence8: I'll be leaving from london kings cross and need to leave after 17:15. Question: Who has spoken the sentence 7? (A) User (B) System
Answer: (B) System