You will be given a definition of a task first, then some input of the task.
You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: There are many leaving that day. What time would you like to leave? Sentence2: The TR5106 arrives in Cambridge at 23:23. The travel time is 163 minutes. Can I help you with anything else today? Sentence3: No thank you. I'm looking for a train that is departing from Birmingham New Street heading to Cambridge. Sentence4: I have 23 guesthouses that would meet that criteria. Would you like to narrow it down by area, stars, or price range? Sentence5: That is all I needed! Thank you so much. Sentence6: Can you help me find a guesthouse that includes free wifi? Sentence7: That would be great. Can I have the postcode, phone number, and if they have free parking? Sentence8: acorn guest house is a great place Sentence9: You're welcome! Have a great day! Sentence10: No thank you, I just need the arrival and travel time. Sentence11: The train should leave on thursday and should leave after 20:00. Sentence12: Great. I have a train that leaves at 20:40. Would you like me to book that for you? Sentence13: I'm looking to travel on thursday Sentence14: What day are you wanting to travel on? Sentence15: They do have parking available. I'm sure you'll love it. They're at 154 chesterton road, cb41da and their phone number is 01223353888. Want to book a room? Sentence16: Sure. I need something in the North, and I'd like a 4 star establishment. Question: Who has spoken the sentence 15? (A) User (B) System
Output:
Answer: (B) System