Correct Answer: C

Rationale: Helicobacter pylori is a bacterium known to cause peptic ulcer disease by weakening the protective lining of the stomach and duodenum, leading to inflammation and ulcers. While chronic H. pylori infection is a risk factor for stomach cancer, it is not directly linked to colon cancer (Choice A), hiatal hernia (Choice B), or esophageal varices (Choice D). Therefore, the correct answer is C.

Correct Answer: B

Rationale: The correct answer is B. A cerebrovascular accident (CVA), or stroke, is often caused by a lack of blood flow to part of the brain. This leads to damage in the brain tissue due to the deprived oxygen and nutrients. Choices A, C, and D are incorrect. A blow to the head from a hard object can cause a traumatic brain injury but is not the etiology of a CVA. Excessive exercise like running does not typically lead to a stroke. A ruptured artery in the heart may result in a heart attack, not a cerebrovascular accident.

Correct Answer: C

Rationale: The correct answer is C: Too much dopamine in the brain. Parkinson's disease is characterized by a deficiency of dopamine in the brain, not an excess. This deficiency leads to the motor symptoms associated with the disease. Choices A, B, and D are incorrect. Mobility and functioning are affected in Parkinson's disease due to the lack of dopamine, not an excess. The liver and kidneys are not directly related to Parkinson's disease. Skeletal muscle flaccidity is not typically a primary symptom of Parkinson's disease, which is more characterized by rigidity and tremors.

Correct Answer: C

Rationale: The correct answer is C. In emphysema, impaired oxygenation results from enlarged and permanently inflated alveoli, leading to reduced surface area for gas exchange. Choices A, B, and D are incorrect. In emphysema, bronchioles are not typically filled with mucus, alveoli losing surfactant and collapsing is more characteristic of conditions like atelectasis, and purulent fluid accumulation in the bronchioles is commonly seen in conditions like pneumonia, not emphysema.

Correct Answer: B

Rationale: Cushing's syndrome is characterized by the excessive production of cortisol by the adrenal glands, not growth hormone (Choice A), insulin (Choice C), or ACTH (Choice D). The increased cortisol levels lead to a variety of symptoms associated with Cushing's syndrome.