Final answer:
Blood pressure screening is the activity that illustrates primary prevention, as it aims to identify and manage blood pressure issues before they lead to cardiovascular diseases.
Step-by-step explanation:
The client engaged in several activities related to managing blood pressure and improving cardiovascular health. Among these actions, blood pressure screening is an example of primary prevention. Primary prevention aims to prevent a disease or condition before it occurs. Blood pressure screening helps in identifying individuals with high blood pressure early, which can then be managed through lifestyle changes and medication to prevent complications like a myocardial infarction. On the other hand, cardiac rehabilitation is a form of secondary prevention, as it seeks to improve health after an event like a heart attack. Similarly, the stress management lecture falls into primary prevention by targeting stress reduction to prevent the onset of health issues.