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

Sentence1: Sure, when do you want to leave? Sentence2: Train TR4931 leaves Tuesday at 10:40 and arrives by 13:23 in Cambridge. Would you like to book this train? Sentence3: Yes, I would like to book for 3 people. Sentence4: I need a train to Cambridge. I am currently at Birmingham New Street. Sentence5: Sure i will find you one and inform you as soon as possible Sentence6: Great! Thanks so much! Can you also help me find a guesthouse? Sentence7: Tuesday, I'd like to arrive by 14:00, please. Sentence8: Booking was successful, the total fee is 225.3 GBP payable at the station . Reference number is : 8S88SBMF . Question: Who has spoken the sentence 3? (A) User (B) System
Answer: (B) System