What does the size principle of motor unit recruitment state?

• A. Large motor units are recruited first to maximize force and precision.
• B. Small motor units (low-threshold) are recruited first for precision; as force demands increase, larger high-threshold motor units are recruited.
• C. Motor units are recruited randomly with no size-related pattern.
• D. Only one motor unit is activated at any given time during contraction.

Answer: (B)