**Core Concept**
The case describes a child with recurrent pneumonia and delayed passage of meconium, suggesting an anatomical or functional issue with the gastrointestinal tract that may be related to the respiratory system.

**Why the Correct Answer is Right**
The most likely diagnosis is a condition known as **Cystic Fibrosis (CF)**, which is a genetic disorder that affects the respiratory, digestive, and reproductive systems. CF is caused by mutations in the CFTR gene, leading to the production of thick, sticky mucus that clogs the airways and traps bacteria, resulting in recurrent respiratory infections. The delayed passage of meconium is a common symptom of CF due to the abnormal secretion of mucus in the gastrointestinal tract.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the case description.
* **Option B:** This option may be related to the case description, but it is not the most likely diagnosis.
* **Option D:** This option is not a common diagnosis for recurrent pneumonia and delayed meconium passage.

**Clinical Pearl / High-Yield Fact**
CF is often associated with a salty taste in the skin due to the abnormal secretion of sweat, which can be used as a diagnostic test.

**Correct Answer:** C. Cystic Fibrosis.