Detailed Instructions: You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.
Q: Sentence1: I prefer something in the north. And a guesthouse would be better. Sentence2: Da vinci pizzeria is located at 20 Milton Road Chesterton, postcode cb41jy and their phone number is 01223351707. Sentence3: I found two cheap places in the north. 1 indian on Victoria Ave and 1 italian at 20 Milton Rd both in Chesterton. Is that all? Sentence4: Please book it for 1 people for 2 nights starting from friday. Sentence5: No, but free wifi and four star please. Sentence6: You've been successfully booked and your reference number is TJZMY6L9 . Is there anything else you need? Sentence7: Enjoy your stay! Sentence8: Let's try the Italian one. Can I get the postcode and phone number for it, too? Sentence9: No, that would be all. Thanks. Bye. Sentence10: Great, thank you for all your help today. Sentence11: Are there any 4-star places to stay that also have free wifi? Sentence12: Yes, there are 21 places found. Do you have a specific area in mind? Sentence13: Anything else I can help with? Sentence14: The Acorn Guest House is a nice 4 star guesthouse in the north with free wifi. Would you like me to book a room? Sentence15: Yes, I'm also looking for a cheap place to eat that's also in the north. Sentence16: I have eight places, do you have a price range in mind? Question: Who has spoken the sentence 15? (A) User (B) System
A:
Answer: (B) System