Final answer:
Admitting a patient following open heart surgery to the cardiovascular intensive care unit is a nursing activity found in a tertiary health care environment.
Step-by-step explanation:
In a tertiary health care environment, the nursing activity that is typically found is admitting a patient following open heart surgery to the cardiovascular intensive care unit (ICU) (a). This is because the cardiovascular ICU specializes in providing intensive care for patients who have undergone heart surgeries or interventions. The other options mentioned, working the triage desk in the emergency department (b), providing well-baby care in a clinic (c), and administering influenza immunizations at a senior living facility (d), are activities that are typically found in primary or secondary health care environments.