Which of the following vital signs indicates a patient's heart rate?

The vital sign that indicates a patient's heart rate is the pulse. The pulse is a direct measure of blood flow and is felt as a rhythmic expansion and contraction of the arteries, which corresponds to each heartbeat. By palpating the pulse at various points on the body, such as the wrist or neck, healthcare providers can determine how many times the heart beats per minute, giving them important information about a patient's cardiovascular health.

Blood pressure reflects the force of blood against the walls of the arteries but does not provide a direct measure of heart rate; instead, it gives information about the pressure in the circulatory system. Temperature is a measure of the body's thermal state and does not relate to heart activity. Respiratory rate counts the number of breaths a person takes in a minute, which is separate from how fast the heart is beating. Therefore, the pulse is the only option that directly indicates the heart rate.