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