Mechanism of muscle contraction is best explained by the sliding filament theory which states that contraction of a muscle fibre takes places by the sliding of the thin filaments over the thick filaments. Organize sequence of contraction and choose correct option:

(i) Action potential spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm.

(ii) This pull the attached actin filaments towards the center of A-band

(iii) Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.

(iv) Increase in Ca ++ level leads to the binding of calcium with a subunit of troponin on action filaments and thereby remove the masking of active sites for myosin.

(v) Signal sent by the central nervous system (CNS) via a motor neuron.

(vi) The Z-line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.

(vii) A neural signal reaching neuromuscular junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma.