Q: You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.
Sentence1: I have train TR0077 that leaves at 9:01 and arrives at 11:44. Would you like me to book it for you? Sentence2: Thank you. I need to find a train from Cambridge to Birmingham New Street leaving on Tuesday and I need it to arrive by 12:45. Sentence3: I would prefer the centre of town. Sentence4: I have a number of restaurants available. Is there a particular area of the city where you would like to go? Sentence5: You're welcome. Did you need more help? Sentence6: can you book a table for 3 on monday at 18:45 Sentence7: That is everything that I need. Sentence8: You are great thanks ! Sentence9: Glad I could help. Have a great day. Sentence10: I highly recommend Riverside Brasserie. It's located at Doubletree by Hilton Cambridge Granta Place Mill Lane. Is there anything else i can help you with? Sentence11: Yes for sure! That booking was successful and your reference number is L6EX6O5W . Sentence12: That sounds perfect. Could you book it for the same group of people, please? Sentence13: Where can I find a moderately priced restaurant that serves European food? Sentence14: I booked it for you. reference number is J92CR71U . Anything else today? Question: Who has spoken the sentence 4? (A) User (B) System
A:
Answer: (A) User