Detailed Instructions: You are shown a conversation between a user and system. Identify who has spoken the indicated sentence based on the conversation.
Q: Sentence1: The car is a white volkswagen. May I help you with anything else? Sentence2: I need to return back to the hotel from the restaurant. Sentence3: Possibly, does this guesthouse hotel offer free parking and free wifi? Sentence4: The Allenbell is located in the East area. Would you like its address? Sentence5: What price range do you have for vegetarian food in the centre area? Sentence6: Yes. We have two restaurants that meet your criteria. Would you like me to book one for you? Sentence7: All right, I have booked you a taxi from the restaurant back to your lodgings. It will be a white volkswagen, and it will arrive to pick you up at 10:00. Is there anything else you need? Sentence8: That could work. Where is Allenbell located? Sentence9: I just need the address for one of the restaurants. Sentence10: You are welcome. Have a great day, goodbye. Sentence11: I'd be happy to help with your request, but first I will need to know what your destination is from the restaurant. Sentence12: Are there any that serve spanish food instead? Preferably in the center area as well. Sentence13: Thank you. The last thing I think I need is a taxi. To pick me up at the restaurant by 10.00? Sentence14: Yes I will also need the contact number for the taxi. Thanks Sentence15: The a and b guest house meets your needs. Would you like to book it? Sentence16: I'm looking for a nice guesthouse to stay at during my trip to Cambridge. Anything with a 4 star rating will do. Sentence17: I am also looking for a cheap restaurant in the area that serves vegetarian food. Sentence18: The address for La Tasca is 14 -16 Bridge Street. Sentence19: How about Allenbell? This meets all your criteria. Sentence20: No, that is all! Thank you very much! Sentence21: There are no results for a vegetarian restaurant in any price range in the centre area. Would you like to broaden your search to another area? Sentence22: What is the car type that will be sent? Sentence23: The contact number is 07800878036. Anything else I can do for you? Sentence24: I'm not finding any cheap vegetarian restaurants. Is there something else you'd like to look for? Question: Who has spoken the sentence 20? (A) User (B) System
A:
Answer: (A) User