Which word in the sentence is a predicate nominative? Could you explain why?

1st sentence —B. prize
2nd sentence —A. captain
A predicate nominative is a noun or pronoun that renames the subject of the sentence.
A predicate nominative follows a linking verb.
In the first sentence, the subject is one .
However, from the clause before it, one is understood to refer to medal .
A silver one is the prize for the runner-up.
In the second sentence, the subject is quarterback .
The quarterback of the team will become the captain after this season.