Choose the correct statement.
a. Stroke volume multiplier by cardiac output gives heart rate
b. Heart rate multiplied by cardiac output gives the stroke volume
c. Cardiac output divided by heart rate gives the stroke volume
d. Stroke volume divided by heart rate gives the cardiac output

Hint: The heart is an important muscular organ in most animals. Blood is pumped by the heart through the blood vessels of the circulatory system. Circulation of blood carries oxygen and nutrients to the body. The heart carries metabolic waste like carbon dioxide to the lungs. The heart has four chambers, upper left, and right auricle, and lower left and right ventricle.

Complete answer:
• The volume of blood pumped by the left ventricle into the aorta per minute is known as the cardiac output.
• Cardiac output is calculated by
$\text{Cardiac output} \to \text{Heart rate(HR)} \times \text{Stroke volume}$
• The amount of blood supplied to the heart by the veins is the stroke volume(SV).
• By using the above formula, we can calculate the stroke volume as
• Stroke volume is the measure of cardiac output divided by heart rate.
$\text{SV} \to \dfrac{\text{Cardiac output}}{HR}$
• So, the cardiac output divided by heart rate gives the stroke volume.
• Stroke volume is the difference between end-systolic and end-diastolic volumes.

Hence, the correct answer is option (C).

Additional information:
• Change in the heart rate and stroke volume affects the cardiac output. Primary factors include autonomic innervation, hormones, and blood volume reflexes. Secondary factors are body temperature, sex, age, extracellular fluid ion concentration, and emotions.
• Bradycardia can low cardiac output.
• Factors that determine the stroke volume index are preload, contractility, and afterload.

Note: The volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction is the stroke volume. Stroke volume is measured by cardiac output divided by heart rate. Aerobic exercise training increases the stroke volume which in turn decreases the heart rate. Preload on the heart can be increased by increasing end-diastolic volume(EDV). An increase in the stroke volume can increase arterial blood pressure.