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: Ashley hotel is available, would that work for you? Sentence2: Thank you and enjoy your visit to cambridge! Sentence3: Yes, I'd like to book for three people please. Sentence4: Thank you for contacting Cambridge TownInfo centre. Goodbye! Sentence5: I've booked you 3 seats on the TR3720 with a total fee of 30.29 GBP which is payable at the station. The reference number is Y3ATC2SJ . Sentence6: I have train TR3634 leaving cambridge and arriving london kings cross at 13:51. Will that work for you? Sentence7: Sorry about all that confusion. I think I've found you a train. TR3720 is the closest in time, leaving the airport 13:24, arriving Cambridge 13:52. Would you like a seat reserved? Sentence8: Thank you. Im also looking for a hotel in the north in the moderate price range. Sentence9: I need the train to go to cambridge and leave from stansted airport. Sentence10: I reserved a seat for you on the 05:24 train. Your reference number is9BQT5T9M . Your ticket of 10.1 GBP is payable when you get to the station. Sentence11: Booking was successful, you reference number is DEMBOPOR, can I assist with anything else? Sentence12: No that is everything I need today. Thank you. Sentence13: I need a train from Stansted Airport to Cambridge, arriving by 14:45 on Wednesday, please... Sentence14: Great, that's all I needed. Thank you! Sentence15: Yes, I need a train for wednesday arriving at 14:45. Sentence16: Sure, can you book it for 2 nights and 3 people? Question: Who has spoken the sentence 12? (A) User (B) System
Answer: (A) User