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

Sentence1: There aren't any hotels, but there is a guesthouse with 4 stars. It's called the Worth House. Would you like more information? Sentence2: I do not need to book it. I need a train to depart from leicester. Sentence3: Yes book 2 seats please and I'll need the train ID. Also book the Worth House guesthouse for 3 people and 4 nights. And give me the reference number please. Sentence4: Ok, there are many trains leaving leicester on thursday. Where will you be traveling to and what time would you like to arrive by? Sentence5: No thank you that will be all Sentence6: What day will you be traveling? Sentence7: I need to leave for Cambridge after 13:45. Don't let me forget to back track and check on another place to stay please. Sentence8: I am looking for a place to stay in the north while I'm there. Sentence9: Sure, could you give me their name and postcode? Sentence10: Thank you so much! Sentence11: I'll be traveling on Thursday. Sentence12: Before you book it, I need the price and I need the approximate travel time. Sentence13: I am planning a trip in Cambridge Sentence14: I have the 14:09 train leaving from Leicester. Would you like me to book that for you? Sentence15: Great! How can I help you plan your trip? Sentence16: Yes, please book it for me. Sentence17: Have a great trip! Enjoy your day. Sentence18: You are quite welcome, we are happy to help. Enjoy your trip! Sentence19: Okay. I have booked you 2 tickets on the TR2361. The total fee of 75.59 is payable at the station. The reference number is 5VFA0ZBS . Sentence20: The Worth House is in postcode cb41da. Would you like me to book it for you? Sentence21: I would prefer a hotel that is nice but in the cheaper price range. Sentence22: There are 13 places to stay in the north and all but 2 are guesthouses. Which is your preference? What is your pricerange? Sentence23: Sure. The trip itself is approximately 105 minutes. It costs 37.80 pounds. Would you like to book a train? Sentence24: I can, what are your arrival details? Question: Who has spoken the sentence 7? (A) User (B) System
Answer: (B) System