The correct option is C Less than the Audible range of Human being
The human heart beats about 72 times in a minute. Therefore, frequency of our heart beat is 72/60 or 1.2 Hz. This frequency is much less than the audible range. It is a blessing in disguise that we cannot hear sound produced by the heart, movement of muscles and body organs. We would have otherwise remained restless and confused due to unwanted and undesirable sounds produced by the above activities in our body.