Relaxation of skeletal muscle is caused by

A) Reuptake of activator Ca²⁺ by the SR Ca-ATPase pump
B) Efflux of Ca²⁺ into the extracellular space
C) Uptake of activator Ca²⁺ into the mitochondria
D) Closing of the ryanodine-sensitive Ca²⁺channel
E) Binding of Ca²⁺ to calsequestrin