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 need to know what day you will be arriving and how many nights and how many people will be staying. Sentence2: Sure, which part of town are you interested in? Sentence3: There is also churchill college on the west side. Their postcode is cb30ds. Sentence4: I just need a reference number for the reservation. Sentence5: what dad do i reserve and for how many? Sentence6: No that will be all thank you. Sentence7: Well I have Christ College in the city center and their postcode is cb23bu. Sentence8: Home from Home is a guest house located on Milton Road in the north area. Do you need additional information? Sentence9: I am looking for a college in town Sentence10: You are welcome, enjoy your stay. Sentence11: Do you have any other suggestions? Sentence12: Booking was successful. Reference number is : F9WOFY5C . Anything else I can help with? Sentence13: there will be 3 people and 4 nights from thursday Sentence14: Area does not matter. You pick, just let me know the area and postcode please. Sentence15: Thank you. I also need a hotel called home from home. Sentence16: i don't need any dads reserved. i already have one. Question: Who has spoken the sentence 15? (A) User (B) System
Answer: (B) System