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 want the one in the north please Sentence2: Yes, the arbury guest house offers internet Sentence3: I have you booked for a room on Wednesday, for 5 nights, for two people. Your reference number is JHI0YPSS . Would you like help with anything else? Sentence4: That sounds like a good option! Does it include internet? I won't be needing it during my stay, but I'd like to know. Sentence5: There are four! 3 in the centre, and 1 in the north! Sentence6: looking for a restaurant. The restaurant should serve chinese food and should be in the same price range as the hotel Sentence7: Ok. Can we look for something on the north side? Sentence8: Thank you for contacting us and have a nice day. Sentence9: A blue tesla will be picking you up in time to arrive at the restaurant by 18:45. Their Contact number is 07398063187. Is there anything else I can assist you with? Sentence10: golden wok is what you're looking for, can i book it for you? Sentence11: Could I also get a taxi to go from the hotel to the restaurant please? Sentence12: Booked! The reference number is V9O804ND . Is there anything else I can help you with today? Sentence13: Yes, please book golden wok for 2 people at 18:45 on Wednesday. Sentence14: I would like to find a guesthouse to stay in that's in the expensive price range. Can you help me? Sentence15: That is all, thanks. Sentence16: How many people and how many days would you like to book for? Sentence17: There are several moderately priced guesthouses in the North. Arbury Lodge, perhaps? It has a 4 star rating. Sentence18: There are zero guesthouses in the expensive range. Would you like to explore hotels or other price ranges? Sentence19: Please book for 2 people, for 5 nights, starting from Wednesday. Sentence20: Can you book it for me? Question: Who has spoken the sentence 15? (A) User (B) System
Answer: (B) System