Given the task definition and input, reply with output. You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.

Sentence1: I am looking a restaurant in the Centre Cambridge area that serve gastropub food. Sentence2: I have one result for you. It is cityroomz, a 0 star hotel. Do you want to book this? Sentence3: Can you book for 2 nights> Sentence4: I am unable to make a booking for that right now. Is there anything else I can do for you? Sentence5: Moderate price range. Sentence6: I have booked you a car. It's a blue Skoda, and the contact number is 07324436761. Sentence7: Your room is reserved under ref# XP513560 . Is there anything else I can help you with today? Sentence8: I will also need a taxi to take me to the restaurant and hotel. Sentence9: I can find it, but please give me the reference number for the reservation. Nil is such a creative name for a restaurant! Sentence10: Thanks, that's all I needed today. Goodbye! Sentence11: I want to make sure it arrives the restaurant by the booked time. Sentence12: The Nil moderately priced restaurant is in the centre and serves gastropub food. Would you like a reservation? Sentence13: Yes, it most certainly is. The booking was successful, and they will hold your table for 15 minutes. The booking number is CXFENRLZ . Anything else I can assist you with? Sentence14: Does it have free wifi? Sentence15: I also need a place to stay, moderately price, centre area, doesn't matter whether or not it has wifi. Sentence16: Yes it does actually. Sentence17: Yes, I can make the reservation would you like their address? Sentence18: Great, I'm glad I could help! Bye! Sentence19: Oh yessiree, tuesday 6 people and 5 nights please Sentence20: When would you like to arrive by. Sentence21: I have 3 in the centre of town,what price range please? Sentence22: That would be great. Can you make if for a party of 6 on Tuesday at 15:30? Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User