How Do Osmotic Laxatives Reduce Constipation

How do osmotic laxatives reduce constipation?

A) They cause retention of fluid in the bowel,increasing the water content in stool.
B) They add bulk to the stool,which increases stool mass that stimulates peristalsis.
C) They soften stool,allowing the stool to mix with fatty substances,making it easier to eliminate.
D) They cause chemical irritation of nerve receptors in the intestinal lining,which then triggers peristalsis.