Which Best Describes "Rigor Mortis

Which best describes "rigor mortis?"

A) Lack of ATP following death causes cross-bridges to remain tightly bound to actin.
B) Lack of ATP following death causes calcium to remain in the cytosol,continuously stimulating cross-bridge cycling.
C) Repeated,high-frequency action potentials to a skeletal muscle fiber causes sustained contraction following death.
D) Following death,calcium-activated proteases degrade all proteins in skeletal muscle fibers,making muscles limp.
E) Build-up of K+ in T-tubules causes constant,tetanic contractions of skeletal muscles that last for about 12 hours following death.