Answer:
The correct answer is: nerviosamente.
Explanation:
There is a very simple way of making adverbs out of adjectives in Spanish. Those are mostly adverbs of manner (nerviosamente, tranquilamente, rápidamente, etc. - HOW?). We create them by adding a suffix -mente to the adjective.
alegre + mente = alegremente (happily)
triste + mente = tristemente (sadly)
We always take the singular form of the adjective (alegre and not alegres). If the adjective ends in -o, as in our case (nervios-o), we will always take the feminine form, ending in -a.
adjective: nervioso
adverb: nerviosa + mente = nerviosamente
