Correct Answer: B

Rationale: A pulmonary embolism is commonly caused by a blood clot that originates in the venous system of the lower extremity and travels to the lungs, blocking blood flow. This clot is known as a venous thromboembolism. An autoimmune disorder (Choice A) is not typically associated with pulmonary embolism. Intracranial pressure (Choice C) refers to pressure inside the skull and is unrelated to pulmonary embolism. Hypotension (Choice D) is low blood pressure and is not a common cause of pulmonary embolism.

Correct Answer: C

Rationale: The correct answer is C: Appendicitis. The symptoms described - lower right quadrant abdominal pain, fever, nausea, diarrhea, and tenderness upon palpation - are classic signs of appendicitis. Appendicitis is an inflammatory condition of the appendix that often presents with these symptoms and requires immediate medical attention. Choice A, Pseudomembranous colitis, typically presents with watery diarrhea and is associated with antibiotic use. Choice B, Peptic ulcer disease, commonly presents with epigastric pain related to meals and can be accompanied by nausea or vomiting, but it does not typically cause right lower quadrant pain. Choice D, Esophageal cancer, usually presents with symptoms related to swallowing difficulties, weight loss, and sometimes chest pain, but it is not associated with the symptoms described in the scenario.

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: C

Rationale: The correct answer is C. Osteoporosis is commonly caused by bone loss that occurs with aging, leading to brittle bones. Choice A, poor nutrition in infancy, is not a direct cause of osteoporosis. Choice B, regularly weight-bearing exercise, actually helps in maintaining bone density and strength, reducing the risk of osteoporosis. Choice D, cerebral palsy and associated disorders, is not a common cause of osteoporosis.

Correct Answer: A

Rationale: The correct answer is A. Persistent chest pain that may radiate to the arm is a classic symptom of myocardial infarction. This pain is typically described as crushing, pressure-like, or squeezing. Choice B is incorrect because brief sternal chest pain on inspiration is not characteristic of myocardial infarction. Choice C is incorrect because rapid respirations with left-sided weakness and numbness are not typical symptoms of myocardial infarction. Choice D is incorrect because left upper quadrant abdominal pain that radiates to the back and shoulder is not a common presentation of myocardial infarction.