**Core Concept**
Congenital hypertrophic pyloric stenosis (CHPS) is a condition characterized by the thickening of the pyloric muscle, leading to gastric outlet obstruction. This condition typically presents with non-bilious projectile vomiting in infants.

**Why the Correct Answer is Right**
CHPS usually presents in the second week of life, with the peak incidence around 3-4 weeks. This is because the thickening of the pyloric muscle is a gradual process, and it takes some time for symptoms to become apparent. The condition is often associated with an increased incidence in males, and a family history of CHPS can also be a risk factor. The pathophysiology involves the hyperplasia of the smooth muscle cells in the pyloric muscle, leading to an increase in the pyloric muscle thickness and subsequent obstruction.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because CHPS typically presents later than within 2 days after birth. Early presentation is more suggestive of other conditions such as pyloric atresia or pyloric stenosis due to other causes.
**Option B:** This option is incorrect because while CHPS can present around 1 week after birth, the peak incidence is usually around 2-3 weeks.
**Option D:** This option is incorrect because CHPS typically presents within the first few weeks of life, not around 2 months after birth.

**Clinical Pearl / High-Yield Fact**
CHPS is a classic example of a condition that presents with projectile non-bilious vomiting in infants. It is essential to rule out other causes of vomiting, such as pyloric atresia, duodenal atresia, or intestinal obstruction, before diagnosing CHPS.

**✓ Correct Answer: C. Around 2 weeks after birth**