During muscle contraction in humans,the:

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:

The mechanism of muscle contraction is best explained by:

The triceps muscle connects the ulna with which of the following bones?

Cardiac muscle fibres are

Which of the following is not a contractile protein?