**Core Concept**
Morbid obesity is a severe form of obesity characterized by a BMI ≥ 40. It is associated with various comorbidities, including type 2 diabetes, hypertension, dyslipidemia, and cardiovascular disease. The pathophysiology of morbid obesity involves insulin resistance, inflammation, and metabolic dysregulation.

**Why the Correct Answer is Right**
The correct answer is **Sleep Apnea**. Morbid obesity is strongly associated with obstructive sleep apnea (OSA), which is a serious sleep disorder characterized by repeated episodes of partial or complete upper airway obstruction during sleep. The excess body fat in morbid obesity can lead to a narrow airway, contributing to OSA. The prevalence of OSA in morbidly obese individuals is estimated to be around 70-80%.

**Why Each Wrong Option is Incorrect**
**Option A:** Hypothyroidism is not a direct consequence of morbid obesity. While obesity can contribute to secondary hypothyroidism due to decreased peripheral conversion of T4 to T3, it is not the most common association with morbid obesity.

**Option B:** Hyperparathyroidism is not typically associated with morbid obesity. The primary causes of hyperparathyroidism are parathyroid tumors or parathyroid gland hyperplasia.

**Option C:** Nonalcoholic fatty liver disease (NAFLD) is actually a common association with morbid obesity. The pathophysiology of NAFLD involves insulin resistance, metabolic dysregulation, and fatty acid accumulation in hepatocytes.

**Clinical Pearl / High-Yield Fact**
The association between morbid obesity and sleep apnea is so strong that the American Academy of Sleep Medicine recommends screening for OSA in all patients with a BMI ≥ 35.

**Correct Answer: C. Nonalcoholic fatty liver disease (NAFLD)**