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

Sentence1: How about the Alexander bed and breakfast in the centre? It is a cheap 4 star guesthouse with free internet and wifi. Sentence2: That sounds like it might work. Could you check availability for two people this weekend? Sentence3: Does this place include free parking? Sentence4: I am unsure at this time. Sentence5: I am glad to help. Have a nice day. Bye. Sentence6: I live in the centre of town and want to see if I can find a reasonable room for my parents to stay while they are visiting. Sentence7: Okay, would you like some more information about that hotel? Sentence8: You have been very helpful. I have everything I need, thanks. Bye Sentence9: The address is 56 saint barnabas road. Sentence10: What day are they arriving, and how many nights are they staying? Sentence11: The alexander bed and breakfast is a cheap, 4 star guesthouse in the centre area, It has wifi and parking. Does this fit your needs? Sentence12: Can you tell me what the address is? Question: Who has spoken the sentence 4? (A) User (B) System
Answer: (A) User