The mechanism of muscle contraction is best explained by:

Myofilaments or myofibrils are

What is the location of troponin in the process of muscle contraction?

$ATP_{ase}$ activity is found in:

Select the correct statements regarding the mechanism of muscle contraction.
$A.$ It is initiated by a signal sent by $\text{CNS}$ via a motor neuron,not a sensory neuron.
$B.$ Neurotransmitter generates an action potential in the sarcolemma.
$C.$ Increased $Ca^{++}$ level leads to the binding of calcium with troponin on actin filaments.
$D.$ Masking of the active site of actin prevents contraction; unmasking leads to contraction.
$E.$ Utilising the energy from $\text{ATP}$ hydrolysis to form a cross-bridge.

What happens when a sub-threshold stimulus is applied to a muscle?