Final answer:
The therapeutic effect of lisinopril, a medication used to treat high blood pressure and heart failure, is indicated by a decrease in blood pressure.
Step-by-step explanation:
Lisinopril is a medication commonly prescribed to treat high blood pressure (hypertension) and heart failure, which falls under the class of drugs known as ACE inhibitors. ACE inhibitors like lisinopril help relax blood vessels, thus lowering blood pressure and reducing the workload on the heart. Therefore, the outcome that indicates a therapeutic effect of lisinopril would be (A) Decreased blood pressure. This aligns with the fact that one of the primary therapeutic effects of cardiovascular medications is the reduction of blood pressure, which is crucial for decreasing the risk of cardiovascular diseases, including stroke.