Not all sounds made by animals serve for communication, and we have only to turn to that extraordinary discovery of echo-location in bats to see a case in which the voice plays a strictly utilitarian role. To get a full appreciation of what this means we must turn first to some recent human inventions. Everyone knows that if a person shouts in the vicinity of a wall or a mountainside, an echo will come back. The further off this solid obstruction, the longer time will elapse for the return of the echo A sound made by tapping on the hull of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps and the recent of the echoes, the depth of the sea at that point can be calculated. So was born the echo-sounding apparatus, now in general use in ships Every solid object will reflect a sound, varying accoridng to the size of and nature of the object. A shoal of fish will do this. So it is a comparatively simple step from locating the sea bottom to locating a shoal of fish. With experience, and with improved apparatus, it is now possible not only to locate a shoal, but to tell it is herring, cod,or other well-known fish, by the pattern of its echo.
A few years ago it was found that contain bats emit squeaks and by receiving the echoes they could locate and steer and by receiving the echoes they could locate and steer clear of obstacle of locate flying insects on which they feed. This echo-location in bats is often compared with radar, the principle of which is similar.
Which one of the following is correct?
In the first paragraph, the writer says that bats use sound for

Options

A. communicating with one another
B. communicating with animals in general
C. some practical purpose
D. fun

Answer

C

Explanation

In the first paragraph, the writer says that bats use sound for some practical purpose. Option .c. explains it all so that would be the correct answer.