What do laxatives primarily do?

Laxatives primarily function by changing stool consistency and speeding up its passage through the intestines. They help alleviate constipation by modifying the water content and bulk of the stool, making it softer and easier to pass. Laxatives can work in various ways: some increase the water in the intestines, others stimulate bowel contractions, and some add bulk to the stool. The overall goal is to promote regular bowel movements and reduce discomfort associated with constipation, thus making option B the accurate choice.

The other options relate to different physiological processes that are not the primary functions of laxatives. For instance, increasing absorption of nutrients is more associated with digestive aids rather than laxatives, which aim to promote elimination instead. Similarly, reducing stomach acid production pertains to antacids or proton pump inhibitors, while improving mental clarity does not connect to the function of laxatives at all; these are instead linked to cognitive enhancers or stimulants.