After the initial setback, the scientist remained remarkably _____, quickly devising new experiments with undiminished enthusiasm.

✓ Correct Answer: Option B

Resilient means able to recover quickly from difficulties. The scientist's quick devising of new experiments with undiminished enthusiasm directly demonstrates resilience after a setback. 'Despondent,' 'irresolute,' and 'wary' describe states contrary to the enthusiastic recovery.