Which of the following is true about synchronous and asynchronous communications? (a) The requester.

Which of the following is true about synchronous and asynchronous communications? (a) The requester of a service must wait for a response from the service in asynchronous communication. (b) In synchronous communication, the requester of a service must wait for a response from the service. (c) Both parties must be active in asynchronous communication. (d) There is no difference between synchronous and asynchronous communication.