Select the option that describes the correct sequence of events in the mechanism of muscle contraction.
A) Release of calcium into the sarcoplasm 
B) Generation of action potential
C) Release of acetyl choline
D) Formation of cross bridge
E) Unmasking of active sites for myosin

The correct sequence of events in the mechanism of muscle contraction is as follows:

Release of acetylcholine: The action potential leads to the release of acetylcholine from the synaptic vesicles at the neuromuscular junction.

Generation of action potential: The muscle contraction process begins with the generation of an action potential, which is an electrical signal that travels along the sarcolemma (muscle cell membrane).

Release of calcium into the sarcoplasm: The action potential triggers the release of calcium ions from the sarcoplasmic reticulum, a specialised organelle within the muscle cell.

Unmasking of active sites for myosin: The binding of calcium ions to Tn-C leads to the unmasking of active sites on actin, allowing myosin heads to bind and initiate muscle contraction.

Formation of cross-bridge: Calcium ions bind to troponin, causing tropomyosin to move away from the active sites on actin. This allows myosin heads to bind to these active sites, forming cross-bridges between actin and myosin.