Choose the correct alternative from the following : - Assertion (A) : Bats can fly in the night.
Reason (R) : Bats emit ultrasonics.

Answer: A. Both A and R are true and R is the correct explanation of A.

Bats can fly in the night because they can trace the obstacle in the path by perceiving the echo of the ultrasonic sound emitted by them after it is reflected by the obstacle.