To identify the linking verb in the sentence, we need to understand the function of linking verbs. Linking verbs do not express action. Instead, they connect the subject of the verb to additional information about the subject.
The given sentence is: "Though he appeared confident during the interview, he remained uncertain about the final outcome."
Conclusion: The correct linking verb in the sentence, given the context and options, is 'remained.' It connects the subject "he" with the attribute "uncertain," confirming his ongoing state.