Choose the option that best completes the sentence using an appropriate…

To select the most appropriate adverb for the sentence "Though unfamiliar with the topic, he responded to the questions ____," we must understand the logical structure established by the conjunction "Though."

Logical Analysis
The Conjunction: "Though" signals a contrast. It sets up an expectation that normally follows from the first clause.

The Expectation: If someone is "unfamiliar with the topic," the expected behavior would be to respond hesitantly, nervously, or cautiously.

The Contrast: Therefore, to complete the sentence, we need an adverb that describes a response opposite to that expectation (i.e., someone who is bold, assured, or knowledgeable).

Conclusion
The most appropriate option is Option 1: confidently. The completed sentence is: "Though unfamiliar with the topic, he responded to the questions confidently."