Which is the correct answer?

I think it is A, but would like a second opinion.

It was not _____ who left the door unlocked this morning.

A. I
B. me
C. myself

You are right. I is a predicate nominative, following the linking verb, was.

I was not me who left the door open

Baltrum is wrong Ms. Sue is right

To determine the correct answer, we need to understand the grammatical role of the pronoun in the sentence. In this case, the pronoun in question is the one that fills the blank after "not."

In this sentence, we need to use the subjective pronoun, which is the pronoun used as the subject of a sentence or clause. The subjective pronouns are "I," "he," "she," "we," "you," and "they."

Now let's analyze the options:

A. "I" is a subjective pronoun. It can be used as the subject of a sentence or clause. So, "It was not I who left the door unlocked this morning" is grammatically correct.

B. "Me" is an objective pronoun. It is used as an object in a sentence or clause. Therefore, it would be incorrect to use "me" in this context.

C. "Myself" is a reflexive pronoun, which refers back to the subject of the sentence. It is not appropriate to use "myself" in this sentence because there is no preceding subject that it can reflect back to.

Based on this analysis, the correct answer would be A. "I."