Which type of laxative works by adding moisture to stools, helping ease their passage?

The choice of an oral stool softener is correct because this type of laxative operates by increasing the moisture content in the stool. By attracting water into the stool, it results in a softer consistency that is easier to pass. This mechanism is particularly helpful for individuals who may be experiencing constipation, as it promotes regular bowel movements without the harsh effects that some other laxatives might have.

While other types of laxatives are designed for specific functions, oral stool softeners specifically target the consistency of the stool. Stimulant laxatives work differently by prompting contractions in the intestines to stimulate bowel movements, rather than focusing on moisture content. Osmotic laxatives draw water into the bowel through osmosis, but this action is more about increasing the volume of the stool and stimulating bowel movements, rather than softening existing stool. Bulk-forming laxatives increase the bulk of the stool by absorbing fluids, which promotes a bowel movement but does not specifically add moisture to the stool itself. Thus, the unique action of oral stool softeners in adding moisture to the stool is what makes this option the correct answer.