The term time dilation refers to which effect?

Is the apparent loss of time of a moving clock as observed by a stationary observer. Thats what i think.

In the theory of relativity, time dilation is a difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from a gravitational mass or masses.

The correct answer is c

Sound energy is produced when an object vibrates. examples are 1- a balloon popping2-a whistle3- a waterfall