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: Ventilation. Ventilation is the process of moving air into the lungs and distributing it to the alveoli for gas exchange. Choice B, Aeration, is not the correct term for this specific process. Choice C, Enclosure vapor, is not related to the movement of air into the lungs. Choice D, Residual volume, refers to the amount of air left in the lungs after maximal expiration and is not the process of moving air into the lungs.

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: 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: B

Rationale: The correct answer is B: Autoimmune destruction of the thyroid gland. In hypothyroidism, the thyroid gland does not produce enough hormones to meet the body's needs. This can be due to autoimmune destruction of the thyroid gland, where the body's immune system mistakenly attacks the thyroid tissue. Choices A, C, and D are incorrect. Overproduction of cortisol is associated with conditions like Cushing's syndrome, overactivity of the thyroid gland is a characteristic of hyperthyroidism, and insufficient iodine intake can lead to goiter but not necessarily hypothyroidism.