I believe a...hope I help
The answer is D
Explanation:
Specific information for each stage of kidney disease
Motor Unit Summation<span> - the degree of contraction of a skeletal muscle is influenced by the number of </span>motor units<span> being stimulated (with a </span>motor unit<span> being a </span>motor<span>neuron plus all of the muscle fibers it innervates; see diagram below).</span>
Blunt force trauma resulting to cracks or breaks to the bone where ever it was.