Concept:Emphatic stress is a spoken emphasis that corrects a wrong detail in a previous question.
Explanation:In this sentence, the emphasized word is JOHN.
Therefore, the question that it answers must contain another person in place of John.
The rest of the sentence, including the verb and the predicate, must remain the same.
Option A, "Was Ernest a football legend?", exactly follows this pattern.
Options B and C change "football legend" to other terms as well.
Option D leaves John as the subject, which makes the stress unnecessary.
So the appropriate question that the spoken sentence answers is the one in option A.
Answer:A. Was Ernest a football legend?