Final answer:
Nonadherence is the correct term used to describe when a patient does not follow through with their medical treatment plan as prescribed by a healthcare provider.
Step-by-step explanation:
Failing to show up for a doctor's appointment, discontinuing a medication before instructed to do so, and not following a diet are examples of nonadherence with medical advice. The correct answer to this question is A) Nonadherence. This term refers to a situation where a patient does not follow their healthcare provider's prescribed treatment plan, which may include medication regimes, appointments, dietary restrictions, or other therapeutic interventions.