The politician's argument, though _____ on the surface, quickly unraveled under close scrutiny, revealing its inherent logical flaws.

✓ Correct Answer: Option C

Specious means superficially plausible, but actually wrong. The argument appearing convincing at first but unraveling under scrutiny perfectly fits this definition. Veracious, cogent, and irrefutable describe arguments that are truthful, convincing, or unchallengeable.