Select the most appropriate option that can substitute the underlined segment in the given sentence.
It was her who first saw the criminal.

The correct option to substitute the underlined segment is she.

Explanation:

In English grammar, when a pronoun follows a form of the linking verb "to be" (such as is, was, were, been), it functions as a subject complement. A subject complement renames or describes the subject of the sentence.

Therefore, a subject pronoun (nominative case) must be used instead of an object pronoun (objective case).

Let's analyze the sentence structure:

- "It was her who first saw the criminal."

- Here, "was" is a linking verb, and the pronoun refers back to the subject performing the action ("who first saw the criminal").

- The object pronoun "her" is incorrect in formal grammar and should be replaced by the subject pronoun "she".

Corrected Sentence: "It was she who first saw the criminal."