Answer:
The correct answer would be B. 18 to 26%.
The muscle efficiency is calculated by dividing mechanical work output by total metabolic cost.
It is estimated that human muscles have an efficiency of about 18% to 26%.
The efficiency is low because most of the energy is lost when food energy is converted into ATP (adenosine triphophate).
In addition, there is second energy loss when energy in the form of ATP is converted into the mechanical energy such as rowing, cycling et cetera.