**Question:** Which one is not true regarding pyloric stenosis?

A. Pyloric stenosis is a condition that affects infants.
B. It is caused by hypertrophy of the smooth muscle cells in the pylorus.
C. The primary symptom is persistent vomiting after feeding.
D. The treatment involves surgery to relieve the obstruction.

**Correct Answer: Option A - Pyloric Stenosis is a condition that affects infants.**

Pyloric stenosis is a congenital disorder that primarily affects infants, particularly boys, during the first few weeks of life. However, it is not limited to infants and can also occur in adults. In contrast, the other options are true statements describing the condition:

**Option B - Pyloric stenosis is caused by hypertrophy of the smooth muscle cells in the pylorus.**

Pyloric stenosis is characterized by the enlargement and thickening of the smooth muscle cells in the pylorus, the muscular ring at the junction of the stomach and the duodenum. This causes a narrowing of the pylorus, obstructing the passage of food and leading to the characteristic symptoms.

**Option C - The primary symptom is persistent vomiting after feeding.**

The most common symptom of pyloric stenosis is persistent vomiting, often seen immediately after feeding, due to the obstruction of the pylorus. This persistent vomiting can lead to dehydration, malnutrition, and weight loss in affected infants.

**Option D - The treatment involves surgery to relieve the obstruction.**

The primary treatment for pyloric stenosis is surgical intervention, specifically the Billroth-I procedure or pyloromyotomy. This surgery aims to relieve the obstruction by creating a new opening in the pylorus or resecting the narrowed segment of the stomach. After surgery, infants typically recover quickly and can resume normal feeding.