Final answer:
The next step after designing an API for it to be discoverable is Documentation and publication. Clear documentation needs to be created, and then the API must be published where potential users can access it.
Step-by-step explanation:
If an API is in the design center and you're looking to move to the next step to make the API discoverable, the answer is C) Documentation and publication. Before an API can be considered discoverable, it should be well-documented. This means providing a clear and concise reference that explains how to use the API, including endpoints, parameters, data formats, and authentication methods. After the documentation is created, the API must be published to a platform where potential consumers can find and learn about it, such as an API marketplace or developer portal. Documentation serves as a contract between the API providers and consumers, ensuring that both parties have a mutual understanding of how the API should be used.