**Core Concept**
Cystic fibrosis (CF) is a genetic disorder characterized by thick, sticky mucus secretions in various organs, particularly the lungs and pancreas. The underlying pathophysiology involves abnormal chloride transport across epithelial cells, leading to an imbalance of electrolytes and water, resulting in dehydrated mucus. This affects multiple exocrine glands, including those in the respiratory, gastrointestinal, and genitourinary systems.

**Why the Correct Answer is Right**
In cystic fibrosis, the thickened mucus obstructs the exocrine glands, particularly those with a high secretory burden. However, the sweat glands, which are also exocrine glands, are not affected by the same pathophysiological mechanism. This is because the ion transport mechanism in sweat glands is different from that in other exocrine glands. The CFTR (cystic fibrosis transmembrane conductance regulator) protein, which is responsible for the disease, is functional in sweat glands, allowing normal chloride transport and sweat production.

**Why Each Wrong Option is Incorrect**
* **Option A:** The respiratory tract's submucosal glands are obstructed due to the thick mucus, leading to recurrent respiratory infections and bronchiectasis.
* **Option B:** The pancreatic ducts are obstructed, resulting in malabsorption of fats and fat-soluble vitamins.
* **Option C:** The male reproductive tract's seminal vesicles are affected, leading to azoospermia and infertility in some males with cystic fibrosis.

**Clinical Pearl / High-Yield Fact**
The sweat test is a diagnostic tool for cystic fibrosis, where a high chloride concentration in sweat indicates the presence of the disease.

**Correct Answer: C. Sweat glands are not obstructed in cystic fibrosis.**