**Core Concept**
Lactase is a crucial intestinal enzyme responsible for hydrolyzing lactose, a disaccharide found in milk and other dairy products, into glucose and galactose. Its deficiency leads to lactose intolerance, manifesting as gastrointestinal symptoms after consuming lactose-containing foods.

**Why the Correct Answer is Right**
Lactase deficiency in children following an attack of severe infectious enteritis is due to the damage caused to the intestinal mucosa and the subsequent loss of lactase-producing cells. This condition is often referred to as secondary lactase deficiency. The small intestine's ability to absorb lactose is compromised, leading to malabsorption and symptoms like diarrhea, bloating, and abdominal cramps.

**Why Each Wrong Option is Incorrect**
**Option A:** The correct answer is not aminopeptidase, as it is not directly related to lactose hydrolysis. Aminopeptidase is involved in the breakdown of peptides into amino acids.
**Option B:** The correct answer is not sucrase, as it is involved in the hydrolysis of sucrose, not lactose. Sucrase deficiency would result in sucrose intolerance.
**Option C:** The correct answer is not maltase, as it is involved in the breakdown of maltose, not lactose. Maltase deficiency would result in maltose intolerance.

**Clinical Pearl / High-Yield Fact**
Infectious enteritis can lead to secondary lactase deficiency due to the damage to the intestinal mucosa. This condition is often temporary and resolves once the intestinal mucosa heals.

**Correct Answer:** C. Maltase is not correct. The correct answer is actually A. Lactase.