Prostaglandins: A. stimulate smooth muscle contraction. B. have four-membered rings and are derived from arachidonic acid. C. are a subset of leukotrienes. D. inhibit the aggregation of platelets. E. inhibit inflammation.

The correct answer is option A, that is, stimulate smooth muscle contraction.

Explanation:

A group of lipids and a hormone that plays an essential role in monitoring the process of the formation of blood clots, stimulation of labor, the flow of blood and inflammation is known as prostaglandins. The hormone prostaglandin takes part in various kinds of body functions like the relaxation and contraction of the smooth muscles at the time of childbirth, monitoring blood pressure, dilation and constriction of blood vessels, and produce inflammation at the site of infection or tissue damage.

Prostaglandins possess five-membered rings and are obtained from the fatty acid, arachidonic acid. At the time of blood vessel injury, thromboxane, that is, a form of prostaglandin enhances the process of blood clot formation so that the injury site gets heal quickly.