Which physiologic change in the large intestine primarily explains constipation?

• A. Autoimmune destruction of large intestinal villi reducing water absorption that always results in constipation as the main clinical feature.
• B. Excessive secretion of water into the lumen leading to liquefied stools and rapid transit, which is the hallmark of constipation.
• C. Increased water absorption and/or slowed transit time causing feces to become harder and drier, making evacuation more difficult.
• D. Failure of the stomach to produce acid leading to downstream colonic hypermotility and watery stools — the primary driver of constipation symptoms.

Answer: (C)