In a skeletal muscle fiber,how many actin filaments surround each myosin filament?

Bone-dissolving cells are known as..........

The superior rectus muscle:

Which mineral element is essential for muscle contraction?

In a $A$ state,the edge of thin filaments on either side of thick filaments $B$ overlap the free ends of $C$ filaments leaving the central part of thick filaments. This central part of thick filament,not overlapped by thin filaments is called $D$ zone.
Choose the correct options to fill the gaps $A, B, C$ and $D$,so as to complete the given $NCERT$ statement.

$A$ sarcomere consists of