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

Sentence1: Great, book me one of those for 8 people. We'll stay from Friday for 5 nights. I'll need a reference number, please. Sentence2: We are happy to help. Thank you for using our service. Sentence3: Certainly, there are 8 guesthouse type accommodations in the north area that are 4 stars. Does parking or wifi matter to you? Sentence4: I need a train leaving friday that will arrive by 16:30 Sentence5: Sure book 1 ticket from kings lynn to cambridge Sentence6: I need a place to stay with a 4 star rating in the north please Sentence7: Booking was successful, the total fee is 78.4 GBP payable at the station. Reference number is : 59LWLXZ4 . Can I help you with anything else? Sentence8: No, I appreciate your help! Sentence9: I need booking for eight people if there is room. If so, book it and send a reference number. Sentence10: Now that we've specified, we have one that arrives at 14:58, the TR6844. Does this still work? Sentence11: Certainly, there are plenty of options, the train that arrives closest to 16:30 arrives at 14:43. Shall I book it, if so for how many riders? Sentence12: I am indifferent to parking but free wifi is a necessity. Sentence13: I booked you what you requested at the avalon hotel. Your reference number is J8LR3GIP . Can we help you with anything else? Sentence14: All the selections have wifi, 7 of the 8 hotels are moderately priced, but one is in the cheaply priced range. Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User