Final answer:
The measure of success according to the statement is the Ability to absorb failure. Success is tied to resilience and learning from difficult experiences, not just the triumphs on easy days. C is the correct answer.
Step-by-step explanation:
The measure of success in the statement is the ability to absorb failure.
This expression emphasizes that success is not merely about triumphing on untroubled days, symbolized by 'the days when the sun shines,' but rather about how one copes with hardships and setbacks—represented by 'the dark, stormy, cloudy days.'
Therefore, it suggests that resilience, or one's capacity to endure and learn from failure, is the true indicator of success. Taking this approach, we should adopt the mindset of working toward success with the belief that it is achievable, and begin our efforts immediately to improve our prospects for success and mitigate the likelihood of failure.