You will be given a passage, and your task is to generate a Yes/No question that is answerable based on the given passage.
Q: The central nervous system is responsible for the orderly recruitment of motor neurons, beginning with the smallest motor units. Henneman's size principle indicates that motor units are recruited from smallest to largest based on the size of the load. For smaller loads requiring less force, slow twitch, low-force, fatigue-resistant muscle fibers are activated prior to the recruitment of the fast twitch, high-force, less fatigue-resistant muscle fibers. Larger motor units are typically composed of faster muscle fibers that generate higher forces.
A: 
does the size of a motor unit vary?