Mr. peters sat between molly and a. i; direct object b. i; object of a preposition c. me; object of a preposition d.

b. I; object of a preposition

Explanation:

For it to be grammatically correct, the answer is I, not me.

Mr.Peters sat between Molly and I.

It is an object of preposition, because the subject (Mr.Peters) is before the verb (sat).

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Mr. peters sat between molly and me.

C. Me; object of a preposition

Explanation:

This is the right sentence as the blank is filled up with me. "Me" is the object of preposition and justly gives the meaning to the sentence. Here "me" showcases the second object other than molly in between which Mr. peter will take the seat. Here the sentence is spoken in direct person and thus "me" is used as the "object of a preposition".