Final answer:
A competency-based reward in the given options is skill-based pay, as it directly incentives employees for acquiring new skills and applying them to their work.
Step-by-step explanation:
The competency-based reward that is mentioned in the list of options is c) skill-based pay. This type of remuneration system directly rewards employees for acquiring new skills or for the scope of skills they are able to apply to their job. Unlike the other options, which either reward employees for their performance as a group (a), for their longevity with the company (d), or are a natural consequence of job advancement (b), skill-based pay incentivizes personal development and competency acquisition. In a skill-based pay system, the emphasis is on rewarding the employee directly for their ability to perform various tasks or roles rather than for the job position they hold.