The speed of contraction of skeletal muscle is related to:

A)The oxidative capacity of the skeletal muscle fiber.
B)The myosin adenosine triphosphatase (ATPase)activity of the skeletal muscle fiber.
C)The level of β-adrenergic stimulation.
D)The rate of Ca⁺⁺ extrusion from the skeletal muscle fiber.
E)The level of myosin light-chain phosphorylation within the muscle fiber.