Correct Answer: B

Rationale: The correct characteristic of coronary artery disease (CAD) is the insufficient delivery of oxygenated blood to the myocardium. CAD is a condition where the coronary arteries become narrowed or blocked, leading to reduced blood flow to the heart muscle. This lack of oxygenated blood can result in chest pain, known as angina, and if a coronary artery becomes completely blocked, it can cause a heart attack. Choices A, C, and D are incorrect. Choice A refers to an issue related to the lymphatic system, choice C is about gas exchange in the lungs, and choice D describes a problem with bile accumulation in the digestive system, none of which are characteristics of CAD.

Correct Answer: B

Rationale: Gigantism is the correct answer. It is a condition caused by excessive growth hormone release before the epiphyseal plates close, leading to abnormal growth. Acromegaly (choice A) is caused by excess growth hormone after the epiphyseal plates close, resulting in enlargement of bones and tissues. Syndrome of inappropriate antidiuretic hormone (choice C) is characterized by the excessive release of antidiuretic hormone, leading to water retention and dilutional hyponatremia. Dwarfism (choice D) is a condition characterized by significantly below-average height.

Correct Answer: A

Rationale: Mifepristone (RU-486) functions by inhibiting the action of progesterone, a hormone crucial for maintaining pregnancy. By blocking progesterone, mifepristone disrupts the uterine environment necessary for pregnancy continuation, ultimately leading to termination. Choice B is incorrect because mifepristone does not increase estrogen levels; instead, it acts on progesterone. Choice C is incorrect as mifepristone's mechanism does not involve altering the uterine lining to prevent implantation. Choice D is incorrect because mifepristone does not directly stimulate uterine contractions; its primary action is through progesterone inhibition.

Correct Answer: A

Rationale: The correct answer is A: Fatigue. Oral contraceptives can sometimes cause fatigue as a side effect. Frequent high blood pressure readings and frequent headaches without aura are less likely to be directly related to the use of oral contraceptives. Nausea and vomiting are common side effects of oral contraceptives but are not the changes typically associated with liver function affecting hormone metabolism as in the case of hepatitis C infection.

Correct Answer: B

Rationale: The correct answer is B: Severe diarrhea. A patient who has recently returned from a trip to Nepal with a nongovernmental organization and is seeking care for amebiasis would most likely have been prompted by the symptom of severe diarrhea. Amebiasis is an infection caused by the parasite Entamoeba histolytica, commonly transmitted through contaminated food or water sources in developing countries like Nepal. The hallmark symptom of amebiasis is dysentery, which is characterized by severe diarrhea with blood or mucus in the stool. Malaise and fatigue (choice A) are nonspecific symptoms that may accompany many illnesses and are not specific to amebiasis. Intermittent fever (choice C) is not a typical presenting symptom of amebiasis, which primarily manifests with gastrointestinal symptoms. Dizziness and confusion (choice D) are also not typical symptoms associated with amebiasis.