In the following question, out of the four alternatives, select the alternative which is the best substitute of the words/sentence.
Place or insert between one thing and another

Let's look at the meanings of the given words:
Interpose: Place or insert between one thing and another.

Oust: Drive out or expel someone from a position or place.

Efface: Erase a mark from a surface; make oneself obscure.

Purge: Rid someone or something of an unwanted quality, condition, or person.

Therefore, the correct option is D.