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

Sentence1: I want to go the Tandoori Palace. Sentence2: Glad to be of service, Goodbye. Sentence3: Is there anything else I can help you with? Sentence4: Thank you so much you've been very helpful. Sentence5: I would be happy to book that, first I will need to know your destination. Sentence6: Can you book me a taxi to arrive by 23:30? Oh, and I am departing from wandlebury country park. Sentence7: 07903665107 is the contact number, I have you in a black honda. Sentence8: No, that will be all. Goodbye. Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User