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: Please book the Varsity for 5 people on tuesday at 17:00. Sentence2: I am showing 5 architecture in the centre. I could recommend all saints church. Sentence3: I am showing two international restaurants near the centre. The Varsity Restaurant and Bloomsbury Restaurant. Would you like more information on either one? Sentence4: Unfortunately, there are no portuguese restaurants that meet your requirements. Can I look for something else for you? Sentence5: How about portuguese food? Sentence6: You're welcome. Have a nice day. Sentence7: I don't have anything that meets those criteria. Can I check something else for you? Sentence8: Sure, your booking was successful. The table will be reserved for 15 minutes, reference number E8SV1E0D . May I assist you with anything else? Sentence9: I am showing 21 restaurants in that area and price. Is there a certain cuisine you would enjoy? Sentence10: That is all thanks. Sentence11: Yes, please find a restaurant in the moderate price range and same area as the attraction. Sentence12: How about some architecture to visit in the center? Sentence13: I would like to find some entertainment in the centre of the city. Sentence14: How about international food? Sentence15: Ok, what's the phone number? Sentence16: They are reachable at 01223452587, anything else that I can assist with? Question: Who has spoken the sentence 15? (A) User (B) System
A:
Answer: (B) System