Final Answer:
Performing active-assistive ROM exercises with a patient is within the nursing assistant's scope of practice.
Step-by-step explanation:
Nursing assistants have defined scopes of practice that involve providing basic patient care under the supervision of licensed healthcare professionals. Option C, performing active-assistive range of motion (ROM) exercises, aligns with these responsibilities. Nursing assistants assist patients with exercises that promote joint flexibility and mobility.
Options A and B involve tasks that are beyond the scope of a nursing assistant, as diagnosing clinical conditions and conducting specialized therapies are responsibilities of licensed healthcare providers. Option D, applying a prescription ointment, typically requires a higher level of training and is usually done by licensed nurses.