Which contractile protein of skeletal muscle is associated with $ATPase$ activity?

Black bands of myofibrils are known as

Contraction of a muscle is caused by

Which of the following muscles act involuntarily?
$(a)$ Striated muscles $(b)$ Smooth muscles
$(c)$ Cardiac muscles $(d)$ Skeletal muscles

Contractile tissues have the following features:
$(i)$ Mesodermal in origin
$(ii)$ They contain stretch receptors
$(iii)$ Rhythmic contractions are seen in them
$(iv)$ They do not fatigue during the life of the animal
Which of the above are characteristics of sphincters?

$A$: Latent period is the interval between the application of an appropriate stimulus and the initiation of contraction.
$R$: Latent period is minimum in cardiac muscle fibres.