Final answer:
An average human heart beats more than 39 million times a year, which correlates to the given answer of approximately 4E7 (40 million), option a.
Step-by-step explanation:
On average, an adult human heart beats at about 75 times per minute. If you calculate that rate over a year, the heart beats approximately 108,000 times per day, which amounts to more than 39 million times in a year. This puts the closest answer to the question as 4E7 (40 million) beats in a year, which is option a. The heart's activities are central to the body's function, as it ejects about 70 mL of blood per contraction and sends a staggering 10,000,000 liters of blood through the circulatory system over the course of a year. Understanding the anatomy and physiology of the heart is crucial to comprehend how this vital organ performs its function.