**Core Concept**
Cystic fibrosis is a genetic disorder characterized by the production of thick, sticky mucus that can clog the airways and trap bacteria, leading to recurrent respiratory infections and malabsorption of fats and fat-soluble vitamins due to pancreatic insufficiency. This condition is caused by mutations in the CFTR gene, which encodes a chloride channel protein.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of cystic fibrosis. The CFTR protein is a chloride channel that regulates the transport of chloride ions across epithelial cell membranes. In individuals with cystic fibrosis, mutations in the CFTR gene lead to the production of a dysfunctional protein that cannot properly transport chloride ions, resulting in the abnormal production of thick, sticky mucus.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the condition described in the scenario.
* **Option B:** While malabsorption is a feature of cystic fibrosis, it is not directly related to a critical protein altered in this condition.
* **Option D:** This option is not related to the pathophysiology of cystic fibrosis.

**Clinical Pearl / High-Yield Fact**
Cystic fibrosis is a classic example of a genetic disorder that affects multiple organ systems, including the respiratory, gastrointestinal, and reproductive systems. The "salty taste" experienced by the mother when kissing her child is due to the abnormal production of salty sweat, which is a hallmark of cystic fibrosis.

**Correct Answer: C. CFTR (Cystic Fibrosis Transmembrane Conductance Regulator)**