<h2>Right answer: rápidamente</h2>
An <u>adverb</u> is a part of the sentence that complements a verb, an adjective, other adverbs and even sentences. Adverbs express circumstances, such as mode, place, time, quantity, affirmation, doubt; answering questions such as: when?, where?, how?, in what way?, among others.
In other words:
<em>The main function of adverbs is to act as modifiers or complements of a verb or verbal phrase
</em>
Now, <u>in Spanish there are several types of adverbs</u>, but in this specific case we are talking about the adverb of manner.
The <u>adverb of manner</u> can be formed by placing the suffix -mente at the end of some adjectives.
As it is the case of the <u>adjective</u> <em>rápido</em> (fast or quick) that changes to an <u>adverb of manner</u> as <em>rápidamente</em> (quickly).