It was roughly shoved into the missionary's back. nominative objective possessive

The correct answer is nominative.

We are supposed to find the case of the pronoun IT in this sentence, and it is nominative. This means that the pronoun is the subject of the sentence, given that this is a passive sentence.

If the sentence went like this - They shoved it roughly into the missionary's back, then the pronoun would be objective. If it said its instead of it, then it would be possessive.