Which physiologic change in the large intestine primarily explains constipation?

Autoimmune destruction of large intestinal villi reducing water absorption that always results in constipation as the main clinical feature.

Excessive secretion of water into the lumen leading to liquefied stools and rapid transit, which is the hallmark of constipation.

Increased water absorption and/or slowed transit time causing feces to become harder and drier, making evacuation more difficult.

Failure of the stomach to produce acid leading to downstream colonic hypermotility and watery stools — the primary driver of constipation symptoms.