You will be given a definition of a task first, then some input 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: How about one that serves European food? Sentence2: No but can I get the phone number, postcode, and address please? Sentence3: No I am truly sorry. Something else perhaps? Sentence4: Great. Thank you! Sentence5: Are there any crossover restaurants in the west? Sentence6: Sorry, that would be 16:07 for arrival time. Can you confirm how many are traveling? Sentence7: Yes I would like a train to bishops stortford please. Sentence8: Yes, departing from Cambridge on Monday. I'd like to get to Bishops Stortford by 18:00, if possible. Sentence9: Thank you for using Cambridge TownInfo centre. Please consider us for your future travel needs. Sentence10: Yes please. Book that. Sentence11: There are no crossover restaurants in the west is there another area you'd like me to look in? Sentence12: I take that back, the TR4283 definitely arrives at 06:07, and departs at 05:29. The booking was successful. The total will be 10.1 GBP, payable at the station. Reference number:2P9BM67Z . Sentence13: Cambridge Lodge Restaurant is a European place in the west that is expensive. Would you like to book a table? Sentence14: I can help you with that. Just to confirm, are you departing from Cambridge or another city? Sentence15: Absolutely. They are located at Cambridge Lodge Hotel 139 Huntingdon Road, City Centre. Their phone number is 01223355166. Their postcode is cb30dq. Anything else I can help with? Sentence16: How about looking for crossover restaurants that are expensive. Doesn't matter the area. Sentence17: I am traveling by myself. I need the train ID also after you book. Sentence18: Train TR4283 arrives at Bishops Stortford by 6:07 and costs 10.10 pounds per ticket. Would you like me to reserve a seat for you? Question: Who has spoken the sentence 4? (A) User (B) System
Output:
Answer: (A) User