Skeletal Muscle Fibers Show a Range of Responses to Different

Multiple Choice

Skeletal muscle fibers show a range of responses to different levels of stimulation because

A) each muscle fiber contraction is "all or none."
B) the availability of Ca²⁺ sets an upper limit to the strength of the contraction.
C) a new contraction can occur only after the resting condition is reached.
D) following stimulation, the fibers stay contracted.
E) individual twitches in quick succession in the same fiber can undergo summation.