Which pronouns refer back to the subject of the sentence?

The choice of reflexive pronouns as the answer is accurate because these pronouns are specifically designed to refer back to the subject of the sentence, thus reflecting the action back on the doer. For instance, in the sentence "She prepared herself for the exam," the reflexive pronoun "herself" refers back to the subject "She," indicating that the action of preparing is directed towards the subject itself.

In contrast, intensive pronouns, while they can look similar to reflexive pronouns, serve a different purpose. They emphasize or intensify the noun they are modifying rather than referring back to the subject. Additionally, reciprocal pronouns express mutual actions between two or more subjects (like "each other" or "one another"), indicating a relationship rather than reflecting the action back on the subject. Subjective pronouns are simply the pronouns that act as the subject in a sentence (e.g., I, you, he, she) and do not refer back to a subject but rather function as the subject itself. Thus, reflexive pronouns are the ones that accurately reflect back on the subject in a sentence.