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

Sentence1: That sounds interesting. Can you tell me their phone number and the cost of entrance? Sentence2: I am looking for a moderate priced place to dine in the centre area. Sentence3: Can you get me a taxi that could take me from the museum to the bistro? Sentence4: I was able to book that taxi for you. Be looking for a white Audi. If you need to contact them, their phone number is 07749170478. Anything else I can do? Sentence5: Entry is free and the phone number is 01223333516. Is there anything else I can help with? Sentence6: I want to leave the museum by 07:45. Sentence7: I don't really care. Can you please suggest one for me? And please include the postcode. Thanks. Sentence8: You're welcome and have a great day. Sentence9: I have several restaurants matching your request. What type of cuisine would you like? Sentence10: I would like to go to a museum. Are there any in the area? Sentence11: No, thank you. That's everything I needed today. Sentence12: What time would you like to travel between the two places? Sentence13: There are 11 different museums in city centre. I find the Museum of Archaeology and Anthropology to be fascinating. Would you like to learn more about them, or keep looking? Sentence14: I recommend The Oak Bistro. They serve British food and the postcode is cb21eg. Would you like me to book a table for you there? Sentence15: No thank you. I did want to go to an attraction in the same area of town. Sentence16: There are 44 attractions located in the centre of town like the restaurant. Is there a particular type you would like to visit? Question: Who has spoken the sentence 15? (A) User (B) System
Answer: (B) System