Latissimus dorsi muscles are

In which of the following,growth is possible through increase in volume?

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.

Choose the correct statements regarding muscle contraction. $A$. $A$ motor neuron carries a signal sent by the Central Nervous System $(CNS)$ to the sarcolemma of the muscle fibre. $B$. The neural signal generates an action potential which causes the release of $Ca^{++}$ into sarcoplasm. $C$. Increase in $Ca^{++}$ inactivates the actin for breaking cross bridges. $D$. Actin binds to the myosin head to form a cross bridge. $E$. Shortening of sarcomere takes place, by pulling actin filaments towards the centre of '$A$' band. Choose the correct answer from the options given below:

Between two successive $M$-lines,there is/are:

Total number of muscles in the human body is: