Which of the Following Is TRUE with Regard to the Sliding

Multiple Choice

Which of the following is TRUE with regard to the sliding filament mechanism of muscle contraction?

A) When a muscle fiber is contracting, the thin fibers are connected to the thick fibers.
B) The muscle relaxes when calcium ions are released into the fluid surrounding the thick and thin filaments.
C) The energy for contraction comes from the breakdown of actin into myosin.
D) When actin pushes the Z discs farther apart, the muscle contracts.