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

Which of the following is not a characteristic feature of the biceps muscle?

Sliding filament theory was given by

In a skeletal muscle fiber,what is the $H$-zone?

Which of the following statements are correct regarding skeletal muscle?
$A$. Muscle bundles are held together by a collagenous connective tissue layer called fascicle.
$B$. Sarcoplasmic reticulum of muscle fibre is a storehouse of calcium ions.
$C$. Striated appearance of skeletal muscle fibre is due to the distribution pattern of actin and myosin proteins.
$D$. $M$ line is considered as the functional unit of contraction called sarcomere.
Choose the most appropriate answer from the options given below:

Total number of muscles in the human body is: