Final answer:
The situations that legally require an agent to consent to medical treatment on behalf of the patient depend on the age and competence of the individual. Minors and individuals who are unable to provide consent themselves may require the consent of a parent, guardian, or legally appointed agent.
Step-by-step explanation:
In the given situations, the legally required consent for medical treatment would depend on the age and competence of the individual. Let's analyze each situation:
- A 16-year-old pregnant self-supporting female: Since she is a minor, the consent of her parents or guardian would be legally required.
- A 25-year-old woman needing chemotherapy: She is of legal age and competent to make her own medical decisions, therefore her consent would be required.
- A 17-year-old male in the military services: Similar to situation 1, since he is a minor, the consent of his parents or guardian would be legally required.
- A 92-year-old mentally competent man: He is of legal age and competent to make his own medical decisions, therefore his consent would be required.
- A 21-year-old man in a coma: In this situation, since the individual is unable to provide consent themselves, a legally appointed agent or healthcare proxy would be required to make medical decisions on their behalf.