Answer:
A. If the oven is turned on now, he will have time to preheat.
Step-by-step explanation:
An antecedent is a word, phrase or clause that a pronoun refers to. When the pronoun and antecedent are not in agreement, the sentence is not clearly expressed, is confusing and vague.
In sentence A, the pronoun and the antecedent are not in agreement because the pronoun "he" does not match its antecedent "the oven". To fix the error, you should replace the pronoun "he" with the pronoun "it" that refers to the oven.