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

Sentence1: I need to book a taxi to take me from Mumford Theatre to go to Darry's Cookhouse and Wine Shop. Sentence2: You are quite welcome. Thanks for using our services. Sentence3: I need to get there by 24:45. Sentence4: That was everything. Thanks!! Sentence5: Your booking is complte, a grey lexus will pick you up. The contact number is 07486674737. Do you need any further assistance? Sentence6: Ok, what time do you want to leave? Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User