Identify the word which the adverb modifies: 

She is running very fast. 

Correct alternative is C) 

Adverbs regulate verbs, adjectives and now and again different adverbs in a sentence. In this sentence, the adverb 'very' modifies the adverb 'fast'. 'Very' attempts to degree the rate at which she is running. Hence, Option C is correct. Option A is inaccurate due to the fact the verb 'is running' isn't being changed via way of means of the adverb 'very' on this sentence. Option B is inaccurate because the adverb 'very' acts because the modifier on this sentence. Option D is inaccurate as adverbs do not regulate pronouns.