Why does your heart never tire of constantly beating to pump blood throughout your body?

The correct answer for above statement is:

D. It consists of cardiac muscle tissues, which means it moves involuntarily.

Explanation:

The human body consists of 3 kinds of muscles, skeletal, smooth and internal organ.All muscles need a gradual provide of blood to supply them with fuel (oxygen and nutrients), and this can be very true of the tireless heart that consumes large amounts of energy. Even once resting, the center consumes twenty times a lot of oxygen than a resting skeletal muscle have.

when comparing the cases, what similarities are there in the cases that suggest one person committed these murders?