Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

Which keyword is essential when calling an asynchronous method in C#?

1. async

2. await

3. Task

4. asynchronous

The correct answer is: await

In C#, the keyword that is essential when calling an asynchronous method is "await." This keyword allows the program to pause the execution of the method until the awaited task completes, enabling non-blocking calls. When you precede an asynchronous method call with "await," it signals to the compiler that the method can be asynchronously paused and resumed, improving responsiveness in applications, especially in UI scenarios or when dealing with I/O operations. The value of "await" lies in its ability to prevent the application from freezing during long-running operations. By using it, you ensure that the calling thread remains free to handle other tasks. While "async" is necessary for the method declaration to indicate that the method contains asynchronous code, it is the "await" keyword that allows you to call and work with the asynchronous method effectively. The other choices involve important aspects of asynchronous programming but do not serve as the core mechanism for calling an asynchronous method directly. "Task" relates to the return type of asynchronous methods, and "asynchronous" is a general descriptor rather than a keyword in C#.