Final answer:
The type of the requirement "The CMS system must be easy to use" is a non-functional requirement.
Step-by-step explanation:
The type of the requirement "The CMS system must be easy to use" is C. Non-functional requirement. A non-functional requirement is a quality or constraint that the system must possess or adhere to. In this case, the ease of use is a non-functional requirement because it is not related to the specific functionality of the CMS system, but rather focuses on the user experience.