## Core Concept
Hirschsprung disease is a congenital condition characterized by the absence of ganglion cells in the distal bowel, leading to a functional obstruction. It primarily affects the large intestine and is caused by a failure of neural crest cells to migrate to the gut during fetal development. The condition results in a contracted, aganglionic segment of bowel that fails to relax and pass stool.

## Why the Correct Answer is Right
The correct answer, ., implies that one of the statements provided about Hirschsprung disease is not true. To determine which, let's examine the typical characteristics of Hirschsprung disease:
- It presents with symptoms of intestinal obstruction, such as abdominal distension, vomiting, and constipation.
- The diagnosis is confirmed by a rectal biopsy showing the absence of ganglion cells.
- Treatment often involves surgical removal of the aganglionic segment.

## Why Each Wrong Option is Incorrect
Without specific details on options A, B, C, and D, we can still provide a general explanation for why incorrect statements about Hirschsprung disease would be wrong:
- **Option A:** If a statement claims that Hirschsprung disease is an acquired condition, it would be incorrect because the disease is congenital.
- **Option B:** If a statement suggests that ganglion cells are present in the affected segment of the bowel, it would be incorrect because the hallmark of Hirschsprung disease is the absence of these cells.
- **Option C:** If a statement implies that the condition only affects the small intestine, it would be incorrect because Hirschsprung disease primarily affects the large intestine (colon).
- **Option D:** If a statement says that the condition is caused by an infectious agent, it would be incorrect because Hirschsprung disease is caused by a developmental failure.

## Clinical Pearl / High-Yield Fact
A key point to remember about Hirschsprung disease is that it often presents in infancy with symptoms of intestinal obstruction. A classic clinical clue is the failure to pass meconium within the first 48 hours of life, which should prompt further investigation.

## Correct Answer: D.