An individual sarcomere of a myofibril consists of:

$A$: All muscles follow the 'All or None' principle.
$R$: All muscles contract either fully or not at all depending upon the availability of a threshold stimulus.

Select the correct statement with reference to muscle structure.
$I.$ Each myosin is a polymerized protein.
$II.$ Many meromyosin constitute one thick filament (myosin).
$III.$ Each meromyosin's tail is called heavy meromyosin $(HMM)$ and head is called light meromyosin $(LMM)$.
$IV.$ The globular head is an active $ATPase$ enzyme and has binding sites for $ATP$ and active sites for actin.
Choose the option with correct statements.

The anaerobic contraction of skeletal muscle causes deposition or accumulation of

In a resting state,the central part of the thick filaments not overlapped by thin filaments is called the .....

At which site do muscle fibers receive stimulation from a motor neuron?