What does blood pressure measure?

Blood pressure is a critical measurement that indicates the force exerted by circulating blood on the walls of blood vessels, particularly the arteries. It is an important vital sign that helps assess the state of a person's cardiovascular health.

The measurement is typically given in two values, systolic and diastolic pressure, which reflect the pressure during heartbeats and the pressure between heartbeats, respectively. Understanding this measurement is vital for detecting conditions such as hypertension or hypotension, which can lead to more serious health issues if not managed properly.

Other options focus on different physiological functions. For instance, measuring oxygen levels in the blood pertains to gas exchange in the lungs rather than blood flow dynamics. Heart rate is a measure of how many times the heart beats in a minute and does not provide information about the pressure within the blood vessels. Body temperature regulation is related to maintaining homeostasis in the body's internal environment, which is distinct from any circulatory measures. Thus, blood pressure specifically captures the pressure aspect of the circulatory system, making it the correct answer.