Answer:
C. The guard talked so quickly that we couldn’t understand his directions.
Step-by-step explanation:
A pronoun is a word that replaces the common or proper noun in a sentence to avoid the repetition of the same noun. Some examples of pronouns are I, we, you, they, he, she, it, etc.
The faulty, vague, or ambiguous pronoun is the one that confuses a reader of the pronoun's antecedent or a sentence in which the reader is unable to know which noun is the pronoun referring to.
In the given statement, the vague pronoun is represented in the use of the 'you' pronoun. The correct pronoun instead of 'you' should be 'we' to make the statement more clear.
Therefore, the correct option is C.