Which of the following can cause a temporary increase in pulse rate?

A temporary increase in pulse rate is commonly observed during sudden exercise because physical activity demands greater blood flow and oxygen delivery to the muscles. When a person engages in sudden exercise, the body responds by increasing the heart rate to pump more oxygenated blood throughout the body. This physiological response is vital for sustaining increased physical activity and ensuring that the muscles receive the necessary nutrients and oxygen to perform effectively.

In contrast, resting positions, low environmental temperature, and sitting quietly generally do not stimulate an increase in pulse rate. Resting typically leads to a decrease in heart rate as the demands on the cardiovascular system lessen. Low environmental temperatures can cause the body to conserve energy and maintain core temperature, often resulting in a more stable or decreased heart rate rather than an increase. Sitting quietly also promotes a calm state, which tends to maintain or lower the pulse rate as there is minimal physical exertion occurring.