Explanation

In the sentence “Wata yarinya siririva ta zo,” the word “siririva” describes how the girl came. It means secretly or quietly. This is an adverb describing the action.

Wait, the question asks for “sifa” which is adjective. Looking closer, if describing the girl herself, we need the word that modifies the noun “yarinya.” Actually “siririva” can function as both.

Descriptive words tell us more about nouns or actions. In this sentence, “siririva” adds information about how something was done.