Actin and myosin proteins are related with

Both proteins,actin and myosin,are arranged in a rod-like structure in the muscles:

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.

Which muscle is responsible for changes in body posture?

Hypertrophy of muscle is

Where is troponin found during muscle contraction?