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

Sentence1: Great, there are 4 options for you here. I personally recommend avalon. Would you like to book? Sentence2: I am looking for a 4 star place to stay. Sentence3: Yes, please book it for 5 people and 5 nights starting from wednesday. Sentence4: You're welcome and thanks for using our help desk. Goodbye. Sentence5: No that is all. Thanks for your help! Sentence6: What area would you like to stay in? Sentence7: Your booking was successful. Reference number is : YB23KVSX . Is there anything else I can help you with? Sentence8: I'd like it to be in the north, and to be a guesthouse. Question: Who has spoken the sentence 7? (A) User (B) System
Answer: (B) System