Correct Answer: B

Rationale: The correct answer is B: Obstruction of the coronary arteries. Angina is primarily caused by a reduced blood flow to the heart due to blockages or narrowing in the coronary arteries. Choice A is incorrect because while increased oxygen demand can contribute to angina symptoms, it is not the primary cause. Choice C is incorrect as angina is not caused by a lack of oxygen in the lungs. Choice D is also incorrect as angina is not related to decreased blood supply to the liver.

Correct Answer: A

Rationale: Thrombocytopenia is characterized by a decreased platelet cell count, leading to an increased risk of bleeding. Therefore, the correct answer is A. Choice B, a decreased white blood cell count, is not typically associated with thrombocytopenia. Choice C, an increased red blood cell count, is not a characteristic finding in thrombocytopenia. Choice D, an increased platelet cell count, is the opposite of what is observed in thrombocytopenia.

Correct Answer: A

Rationale: Leukocytosis is a condition characterized by an elevated white blood cell count, typically in response to infection or inflammation. Therefore, the correct answer is an increased white blood cell count (Choice A). Increased platelet count (Choice B) is not a typical finding in leukocytosis. Choices C and D, decreased white blood cell count and decreased platelet count respectively, are opposite to what would be expected in leukocytosis and are therefore incorrect.

Correct Answer: A

Rationale: The correct answer is A: Respiratory acidosis. In respiratory acidosis, there is an accumulation of CO2 in the blood, leading to a decrease in pH. The elevated PaCO2 of 55 mmHg in the given results indicates hypoventilation, causing respiratory acidosis. Choices B, C, and D are incorrect because the provided data does not show metabolic acidosis, respiratory alkalosis, or metabolic alkalosis.

Correct Answer: A

Rationale: The correct answer is A: Decreased plasma proteins. Edema can be caused by decreased plasma proteins, which reduce the osmotic pressure that keeps fluid in the blood vessels. Hypotension (choice B) is low blood pressure and is not a direct cause of edema. Dehydration (choice C) involves a lack of body fluid, but it is not a direct cause of edema. Polyuria (choice D) is excessive urination and not a direct cause of edema.