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: There are 11 results but the first listing is a and b guest house located at 124 tenison road. Sentence2: I want a particular one called whale of a time, can you find that? Sentence3: Yes! Would you like their information? Sentence4: I will also need a taxi to commute please. Sentence5: Which side of town are you interested in staying? Sentence6: To clarify, you'd like a taxi from Whale of a Time to A and B Guest House, correct? What time would you like the taxi? Sentence7: There are several However I need to know how long your stay is going to be when and for how many please? Sentence8: From A and B Guest House at 01:00 to Whale of a Time, please. Sentence9: Sure, lookout for a black Tesla contact number 07230031614. Can I help you with anything else? Sentence10: Sorry, I didn't understand your last request. I understand that you're looking for a 3 star hotel with internet. Is there a certain area you are interested in staying? Sentence11: i suggest whale of time. i need its address, entrance fee and postcode Sentence12: Whale of a Time is located at Unit 8, Viking Way, Bar Hill. Their postcode is cb238el. Their entrance fee is not listed. Sentence13: Can you help me book a three star hotel with internet? Sentence14: I am also interested in finding a 4 star guesthouse type hotel in the moderate price range with free wifi. Sentence15: Yes please, could i get their address, postcode and entrance fee if they have one? Sentence16: You're welcome! Have a great day! Sentence17: No, that's everything I need today. Thank you. Sentence18: I am not booking a room yet I just need information. Please make a suggestion and provide the address. Question: Who has spoken the sentence 15? (A) User (B) System
Answer: (B) System