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

Sentence1: I'm going to Cambridge from Liverpool Street. On Sunday. Sentence2: Charlie chan is a cheap chinese reasurant in the centre. Phone number is: 01223361763 postcode :cb21db Address: Regent Street City Centre. Do you need anything else? Sentence3: The TR9025 leaves at 11:59 and gets you into London Liverpool Street by 13:27. Would you like to book it? Sentence4: Thanks I'm also looking for a restaurant called Charlie Chan can you find some information for me? Sentence5: Sure, where would you like to go? Sentence6: That would be all thanks ! Sentence7: The train will cost 13.28 pounds a ticket and leaves at 11:59. Sentence8: I need to know the price and travel time please Sentence9: Hi. Can you help me find a train? Sentence10: I need to leave after 11:15. Sentence11: Enjoy your meal sir and you are welcome. Sentence12: I have many trains leaving and arriving all day. Do you have a preference for time of travel? Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User