In this question, sentence is given with blank to be filled in with an appropriate word. Four alternatives are suggested for question. Choose the correct alternative out of the four.
Turn the lights ___ before you go to bed.

Options

A. on
B. off
C. out
D. down

Answer

B

Explanation

both turn off and tum out can be used here, as they mean the same. But we cannot turn out when we talk about a tap/a radio.
turn on (Phr. V.) : to attack somebody suddenly and unexpectedly , to depend on something , to start the flow of electricity, gas, water, etc. by moving a switch, button, etc.
turn out (Phr. V.) : to stop the flow of electricity, gas. water, etc. by moving a switch, button, etc.
turn down (Phr. V.) : to reduce te noise, heat, etc. produced by a piece of equipment by moving its controls
Here, the most appropriate usage is turn off.