What formula represents the relationship between stroke volume and heart rate?

The correct answer reflects the fundamental formula that expresses cardiac output, which is the volume of blood the heart pumps per minute. Cardiac output is calculated by multiplying stroke volume (SV)—the amount of blood ejected by the heart with each beat—by heart rate (HR), which is the number of beats per minute.

This relationship illustrates that cardiac output is dependent on both how much blood is pumped with each beat and how frequently the heart beats. Thus, the formula CO = SV x HR succinctly encompasses this relationship, reinforcing the importance of both stroke volume and heart rate in determining overall cardiovascular health and performance.

Other options provided do not accurately represent the cardiac output calculation. For instance, "HR x SV" and "SV x HR" have the right mathematical approach but do not provide the full context by equating it to cardiac output. "CO = HR + SV" misrepresents the relationship by suggesting addition rather than multiplication. Similarly, "HR + SV" also lacks the necessary mathematical operation to define the relationship accurately.