Which of the Following Statements Regarding Contraction of a Skeletal

Multiple Choice

Which of the following statements regarding contraction of a skeletal muscle fiber is TRUE?

A) Thick filaments shorten when muscle cells contract.
B) Some contractions occur without cross-bridge activation.
C) Contracting muscle fibers do not always shorten.
D) Contraction does not always require the occurrence of an action potential.
E) Contraction only occurs following summation of action potentials from many motor neurons.