It is a dependent clause: a group of words containing a subject and a verb and that does not express a complete thought on its own.
It acts as a noun in a sentence; thus, it can function as a subject, a direct or indirect object, a predicate nominative, or an object of a preposition.
It tends to begin with the words how, that, what, whatever, when, where, whether, which, whichever, who, whoever, whom, whomever, or why.
Therefore,<u> "Whoever is interested in the past" is a noun clause</u> because it does not express a complete thought on its own, meaning that it needs another clause to depend on, it acts as a noun and the subject of the sentence: it is what is dealt with in the sentence, and it begins with the word "whoever."
The correct answer is B. box, because after the word "box" she is describing what she found in it. They are two different things, so you need a comma after box.
