Hiya!
This question isnt fun at all...
but I have information that should actually help if you take the time to read them and compare it to the question's sentence. It'll help you understand hopefully,
A relative adverbs are, "where, when, & why" whereas relative pronouns contain the following, "who, which, whose, whom, that"
An Adjective clause gives more information about a noun or prounoun.
Essential Adjective is needed to make the sentence proper and understanable.
Nonessential Adjectives clauses are set apart with commas, making it nonessential.
Hope this helps!