Which drug class irritates bowel linings to promote bowel movements?

The correct answer is cathartic. Cathartics are a class of drugs specifically designed to induce bowel movements by irritating the lining of the intestines. This irritation stimulates peristalsis, which is the wave-like muscle contractions that facilitate the movement of contents through the digestive tract. As a result, they are effective for treating constipation or preparing the bowels for medical examinations or procedures.

Understanding the other drug classes helps clarify why they are not the correct responses. Decongestants primarily work by reducing nasal congestion and do not have any effect on bowel function. Diuretics are medications that promote the excretion of water and electrolytes through urine, without influencing bowel movements directly. Narcotics, while they have pain-relieving properties, are known to cause constipation rather than promote bowel movements, as they can slow down gastrointestinal motility. This context highlights the unique role of cathartics in promoting bowel health.