The correct answer is option B.
Adverb clauses modify a verb, another adverb or an adjective. They are introduced by subordinate conjunctions such as "although," "as," "if," "than," "until" and "while."
In the example, the adverb clause (as... as) is modifying the adjective it sorrounds.
Option A, "Andrea", is a noun, so it cannot be modified by an adverb clause.
Even though adverb clauses can modify verbs such as "know", alternative C is not possible either because it is clear that the adverb clause (as... as) holds within an adjective to modify.
