**Core Concept**
Congenital Pyloric Stenosis (CPS) is a condition characterized by the narrowing of the pyloric channel due to hypertrophy of the pyloric muscle. This obstruction leads to gastric outflow obstruction, resulting in metabolic disturbances. In the early phase, infants with CPS often experience dehydration, electrolyte imbalances, and metabolic acidosis due to prolonged vomiting.

**Why the Correct Answer is Right**
Infants with CPS typically present with non-bilious projectile vomiting, leading to loss of gastric contents and subsequent dehydration, hypochloremic alkalosis, and metabolic acidosis. The metabolic acidosis is primarily caused by the loss of hydrogen ions from the stomach contents and the subsequent compensatory increase in renal ammonia production.

**Why Each Wrong Option is Incorrect**
* **Option A:** Hypochloremic alkalosis is indeed a common metabolic abnormality in CPS, so this option is correct and should not be included in the distractors.
* **Option B:** Metabolic acidosis is a well-recognized complication of CPS in the early phase, making this option incorrect.
* **Option C:** Dehydration is a key feature of CPS, often leading to hypovolemic shock if left untreated. This option is incorrect as it is a common complication.

**Clinical Pearl / High-Yield Fact**
In infants with suspected CPS, a high index of suspicion is essential. A classic sign is the "olive" mass, which is a palpable, mobile mass in the right upper quadrant representing the hypertrophied pylorus.

**Correct Answer: D.**