What is the preposition in the sentence?

"The children sat under the tree"

ASat
BChildren
CUnder
DThe

Please explain what a preposition is and why the answer is correct.

Verified Answer :

Prepositions are words that are used to indicate a location, time, or direction. In this case, the word "under" would be the preposition since it shows the location of where the children sat.

The word under is a preposition, because it indicates where the children were  / sat.