Question

You should not sleep ________ day.
at
in
by
on

Answer 1

You should not sleep during the day. (During is the right preposition)

What is a preposition?

• In English grammar, prepositions are used to show the connection of a noun or pronoun with the rest of the sentence.
• Prepositions are used to show time, location, and direction, or to connect with an object.
• Some examples of prepositions are: off, in, at, off, over, into, etc.

Thus, the right option can be 'during.'