What is the difference between Synchronous and Asynchronous updates?

A. In synchronous processing, the program waits: control returns to the program only when the task has been completed. 
B. In asynchronous processing, the program does not wait: the system returns control after merely logging the request for execution. 
C. In asynchronous processing, the program waits: control returns to the program only when the task has been completed. 
D. In synchronous processing, the program does not wait: the system returns control after merely logging the request for execution.

Ans: A,B