Which of the Following Statements Is True Regarding Skeletal-Muscle Contraction

Which of the following statements is true regarding skeletal-muscle contraction?

A) The cross-bridge cycle refers to the sequence of events between the time an individual cross bridge binds to a thin filament at the start of a muscle contraction and the time the cross bridge releases the filament at the end of the contraction
B) Excitation-contraction coupling refers to the binding of energized myosin to actin
C) Binding of myosin to actin cannot take place in the absence of calcium ion
D) A single twitch in skeletal muscle lasts about as long as the action potential that caused it
E) All of the choices are true