The correct answer is C. We hiked to the top of the mountain slowly but steadily.
Explanation:
In grammar, an adverb is a word that modifies or describe a verb rather than a noun as in the case of adjectives; additionally, most adverbs can be identified because they commonly end in "-ly" such as slowly, quietly or carefully but other words such as always, now or very also work as adverbs. In the case of adverbial phrases, these are set of words that work as an adverb by usually including one adverb along with other words that complement its meaning or multiple adverbs which answer to the question how?. Considering this, the sentence that adds an adverb phrase is "We hiked to the top of the mountain slowly but steadily" because in this the words "slowly but steadily" describe or modify the action "hiked", both "slowly" and "steadily are adverbs and this answers to the question "how did they hike?" which occurs only in adverbial phrases.
