Put the following phrases in proper order to describe what occurs at the neuromuscular junction to trigger muscle contraction:
I. Receptor sites on sarcolemma.
II. Nerve impulse.
III. Release of Ca+2 from sarcoplasmic reticulum
IV. The neurotransmitter acetylcholine is released
V. Sarcomere shortern
VI. Synaptic cleft
VII. Spread of impulses over sarcolemma on T-tubules
(a) II, IV, I, VI, VII, III, V (b) II, IV, VI, I, VII, III, V
(c) I, II, III, IV, V, VI, VII (d) VII, VI, V, IV, III, II, I