Final answer:
Hirschsprung disease, also known as megacolon, is a condition where a section of the colon is enlarged due to an absence of nerve cells, causing difficulty with bowel movements, and usually requires surgical treatment.
Step-by-step explanation:
Megacolon, specifically Hirschsprung disease, is a condition where a portion of the colon is enlarged because of the lack of proper nerve cells (ganglion cells) in the intestinal wall that regulate the movement of the bowel. This causes difficulty with passing stool and can lead to a dangerous buildup of feces and intestinal blockage.
Affected newborns often have symptoms such as failure to pass meconium within the first days of life, bloating, vomiting, and constipation or severe difficulty with bowel movements. Hirschsprung disease is typically treated with surgery to remove the affected portion of the colon. A correct answer to the question provided would be (a) Enlarged colon. This congenital condition should not be confused with other colon issues like diverticulosis, which involves the formation of pouches in the colon wall, or inflammatory bowel diseases such as Crohn's disease and ulcerative colitis.