You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1:i need a place to dine in the center thats expensive Sentence2: I have several options for you; do you prefer African, Asian, or British food? Sentence3: Any sort of food would be fine, as long as it is a bit expensive. Could I get the phone number for your recommendation?Question: Who has spoken the sentence 2? (A) User (B) System
Solution: Answer: (A) User
Why? The sentence 1 is said by a user because the intent of it says that the information has to be gathered from the system

New input: Sentence1: How about just one night instead? May I have the reference number please? Sentence2: Sunday. Could you please send me the reference number? Sentence3: Yes, I would like a guesthouse with a 0 star rating. Sentence4: El Shaddai sounds fine. I need to reserve it for two adults for two nights, please. Sentence5: There is city centre north b and b, and el shaddai which would you like to book? Sentence6: Sure, the 15:17 train's id is TR7931. Is there anything else I can help you with? Sentence7: I want to depart from london kings cross after 13:30. Sentence8: Sure, the first train leaves at 15:17. Would you like to book it? Sentence9: You are very welcome. Enjoy your stay! Sentence10: There are 200 trains coming to Cambridge on Sunday. Is there a particular time or departure location you're interested in? Sentence11: Great, that was a successful booking, the reference number is 9H97D0MB . Is there anything else I can help with? Sentence12: No that's all, thanks! Sentence13: I am also looking for a place to stay. I would like the hotel to have free parking and free wifi. Sentence14: I'm looking for a train leaving on Sunday that is going to Cambridge. Sentence15: Alright, what day will you be staying? Sentence16: No, I would like to book at a later time, but can I please get the train ID? Sentence17: My listings show almost 30 separate lodgings around town with free wifi and parking! Do you have any other preferences to help me pick one for you? Sentence18: Unfortunately the booking was unsuccessful. Would you like me to book it for another day or duration? Question: Who has spoken the sentence 4? (A) User (B) System
Solution:
Answer: (A) User