<span>The answer is c.the Librarian because she manages all the school’s informational resources</span>
Appositive is defined as a noun, a noun phrase, or a noun clause which sits next to another noun to rename it or to describe it in another way. The sentence can still be completed without an appositive but adding it can present more information about the subject.
I think she is making speculation due to the sadden change of behavior.