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

Sentence1: I found a train for sunday after 21:00 leaving cambridge going to kings lynn. Would you like to book it? Sentence2: Can you find a train departing from Cambridge going to Kings Lynn? Thanks. Sentence3: The reference number is TVFAM55I . Sentence4: I want to leave after 21:00 on sunday. Sentence5: Absolutely! It looks like this is a 47 minute ride. What day and time are you looking to depart? Sentence6: Yes, please book it for 1 and send me a reference number. Question: Who has spoken the sentence 5? (A) User (B) System
Answer: (B) System