I don't know what rules the test wants. I sometimes hear people use subject pronouns even after phrases like "This is ___". In answering the phone, some speakers insist that "This is she" or "This is he" is preferable to "This is her" or "This is him." I don't agree with speakers who believe this, but I've heard the argument before.Hello, Alchan112. Welcome to the forum.
I have a question for owlman5. Yes, "she" is the standard subject pronoun. But the sentence's subject is "They". So why should the "she/her" at the end use a subject pronoun? I'm not disagreeing. I'm just trying to understand the grammar rules.