Respuesta :
Option A, since option B seems to be in an incorrect format for a sentence. Hope this helps :)
Answer:
it is c
Explanation:
The sentence with a vague pronoun error is the following one: Eli is always thinking about computers; it seems to be his only interest. The pronoun "it" in this sentence refers (vaguely and confusingly) to what Eli is always thinking about--a long phrase that doesn't really agree with a singular pronoun like "it" since it sounds singular with the gerund "thinking" but plural with the noun "computers."