The mechanism of contraction in smooth muscle is different from skeletal muscle in that a. atp energizes the sliding process b. the site of calcium regulation differs c. the trigger for contraction is a rise in intracellular calcium d. actin and myosin interact by the sliding filament mechanism

B. The site of calcium regulation differs.

Explanation:

Smooth muscle is an involuntary muscle. It is a form of non-striated muscle.  It is present as the lining over the hollow organs such as stomach, urinary bladder, uterus, arteries, veins, respiratory and reproductive structures.

Skeletal muscle is a voluntary muscle which is actually under the control of the brain. It is a form of striated muscle. It helps in contraction of the muscles and facilitates the locomotion of the body.

The source of calcium for the contraction of the skeletal muscles is the sarcoplasmic reticulum which stores the intracellular calcium.

There are two sources of calcium for the contraction of the smooth muscles these are:

1. The sarcoplasmic reticulum which stores the intracellular calcium.

2. The calcium channels which are present over the cell membrane which stores the extracellular calcium.