**Core Concept**
Cystic fibrosis is a genetic disorder characterized by abnormal thickening of secretions due to mutations in the CFTR gene, leading to impaired chloride transport across epithelial cell membranes. This results in the production of thick, sticky mucus that clogs airways and obstructs pancreatic and intestinal secretions.

**Why the Correct Answer is Right**
The CFTR gene encodes for a chloride channel protein that regulates the transport of chloride ions across epithelial cell membranes. In cystic fibrosis, mutations in the CFTR gene lead to the production of a defective protein that is either absent or non-functional at the cell surface. This results in a decrease in chloride ion secretion, causing the water to be reabsorbed back into the cells, leading to the thickening of secretions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the basic pathology of cystic fibrosis.
**Option B:** While sweat gland dysfunction is a hallmark of cystic fibrosis, it is not the basic pathology of the disease.
**Option C:** This option is incorrect as it does not accurately describe the underlying 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.

**Correct Answer:** D.