A client is prescribed magnesium citrate. What is the mechanism of action for the medication?

A. Draws water into the bowel movement by changing pressure within the intestines: Magnesium citrate is a saline laxative that works by osmosis, drawing water into the intestines. This increases intraluminal pressure and stimulates bowel motility, leading to a bowel movement within hours. B. Water and lipids coat the fecal material facilitating a bowel movement: This describes the action of stool softeners or lubricants like docusate sodium or mineral oil, not magnesium citrate. These agents reduce surface tension or coat stool to ease passage. C. Stimulates the parasympathetic nerves in the intestines to increase peristalsis to cause a bowel movement: Stimulant laxatives like bisacodyl or senna work by directly stimulating intestinal nerves. Magnesium citrate does not act via nerve stimulation. D. The medication absorbs liquid and swells to trigger a bowel movement: This is the mechanism of bulk-forming laxatives such as psyllium, which absorb water and swell to stimulate intestinal activity. Magnesium citrate functions through osmotic fluid retention.