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: You're welcome. Let me know if you think of anything else you need. Sentence2: I have two in that range, in the centre. Is that area the right area for you? Sentence3: I also need a train from Cambridge to London kings cross that leaves on Friday and arrives at 17:00. Sentence4: Need a place to eat with moderate prices, but needs to have russian food. Sentence5: Yes, that area's fine. Can you make a reservation for 6 people on Thursday at 5:30 pm with one of them? Sentence6: Would that be at 5:30 pm (17:30)? Sentence7: Yes, it would. Can you book me 6 tickets for that for Friday please? Sentence8: The closest to that time is TR2420 which leaves Cambridge at 15:00 and arrives in London, Kings Cross at 15:51. Would that meet your needs? Sentence9: Yes, could I have the reference number as well please? Sentence10: Can you try 16:30? Sentence11: What about a Turkish restaurant instead? Sentence12: Unfortunately, I wasn't able to find anything matching your request. Shall we look for a cheap restaurant instead? Sentence13: Sorry booking was unsuccessful. Can you try a different time or day? Sentence14: No, I think that is all for today. Thank you for all your help! Sentence15: I was able to make that reservation at 16:30 your reference number is AKF1B848 . Sentence16: Ok, I've booked 6 tickets, reference number FFVH42H7 . Your total is 141.6 GBP payable at the station. Is there anything else I can help you with? Question: Who has spoken the sentence 9? (A) User (B) System
Answer: (B) System