Why healthy skeletal muscle fiber is isolated

A healthy skeletal muscle fiber is isolated and has no external forces on it.  It has normal intracellular levels of ATP and is bathed in physiological saline.  Which of the following will lead to an increase in the overlap between thin and thick filaments in the muscle fiber?

  A.  An increase in the amount of binding of curare to the nicotinic Acetylcholine Receptors (nAChRs) on the surface of the skeletal muscle.

  B.  An increase in the amount of calcium ions bound to troponin.

  C.  A decrease in the calcium conductance of the membranes of the sarcoplasmic reticulum.