Q: In this task, you are given a conversation between a flight agent and the customer. You are given 4 options and you need to select the goal of the conversation. It is provided as part of customer's context, which has to be one of the following: `book`: Make a new reservation, `cancel`: Cancel an existing reservation, `no_flight`: No flight found for the customer's preference, `no_reservation`: No reservation / No change / No cancellation was made in the conversation, mostly enquiring details
customer: Hello, I am Carol Hill. 
 agent: Hello, how may I aid you today? 
 customer: I want to attend a workshop in my college at Austin, so could you please avail me a flight ticket on 04/21? 
 agent: Sure, please forward your source and destination airport codes? 
 customer: My source and destination airport codes are from FL-MCO to TX-AUS. 
 agent: When would you like to return? 
 customer: I would like to return on 04/23. 
 agent: Sorry no flights are available with your request. 
 customer: No problem, thank you. 
 agent: Thanks for opting us.
A:
no_flight