The principal corrected no one else but … .

Analyze the question: The sentence is "The principal corrected no one else but __." We need the correct pronoun to fill the gap.

Concept: In "no one else but ___", the word but means "except". When but is used as a preposition meaning "except", it takes the objective case (me, him, her, us, them), not the subjective case (I, he, she).

Compare these:

• "Everyone went home but me." (but = except, so objective case)
• "Nobody but him knew the answer."

Step-by-step solution:

1. The subject of the sentence is "The principal", and the verb is "corrected".
2. "No one else but _" is the object of the verb corrected. The principal corrected "no one else except _".
3. Because but here is a preposition meaning "except", and the pronoun is the object of the verb, we need the objective case.

Check the options:

• A. Me is objective case. It fits.
• B. I is subjective case, so it is wrong here.
• C. She is subjective case. It is also wrong, because it would refer to someone other than the principal when the principal is the subject, and it is the wrong case anyway.
• D. Myself is a reflexive pronoun. It needs the subject to be "I" (for example, "I corrected myself"), but the subject here is "the principal", so it does not fit.

Correct sentence: "The principal corrected no one else but me."

Tip: When you see but meaning "except", treat it like except or apart from and use the objective case. Replace but with except and see whether the sentence sounds right: "no one else except me" sounds correct, while "except I" sounds wrong.