Correct Answer: D

Rationale: Osteosarcoma is a type of bone cancer that can be found in any bone but is most commonly located in the long bones of the legs. While it is more prevalent in children and young adults, it can also occur in older individuals like the 60-year-old male patient in this case. Early diagnosis is crucial for a better prognosis in osteosarcoma cases. Therefore, all the statements provided are true regarding osteosarcoma, making option D the correct answer. Option A is accurate as osteosarcoma is more common in children and young adults. Option B is correct as early diagnosis improves the prognosis. Option C is accurate as osteosarcoma is frequently located in the leg bones.

Correct Answer: C

Rationale: When the maternal immune system becomes sensitized against antigens expressed by the fetus, an alloimmune reaction occurs. In this situation, the mother's immune system recognizes the fetus as foreign due to differences in antigens, leading to an immune response against the fetus. Choice A, 'Autoimmune,' is incorrect because it refers to the immune system mistakenly attacking the body's own cells and tissues. Choice B, 'Anaphylaxis,' is not the correct answer as it is a severe allergic reaction that can be life-threatening. Choice D, 'Allergic,' is also incorrect as it refers to an immune response triggered by allergens, not antigens expressed by the fetus.

Correct Answer: A

Rationale: Antibodies are produced by B cells. B cells are specialized white blood cells that generate antibodies as part of the immune response. B cells differentiate into plasma cells that secrete antibodies. T cells play a role in cell-mediated immunity, not antibody production. Helper cells, or helper T cells, assist in activating B cells but do not directly produce antibodies. Memory cells store information about previous infections but do not actively produce antibodies.

Correct Answer: A

Rationale: The correct answer is to take alendronate with a full glass of water and remain upright for at least 30 minutes. This is essential to prevent esophageal irritation and ensure proper absorption. Choice B is incorrect because taking alendronate at bedtime can increase the risk of esophageal irritation due to lying down. Choice C is incorrect as taking alendronate with milk can reduce its absorption. Choice D is incorrect because alendronate should be taken on an empty stomach to enhance its effectiveness.

Correct Answer: A

Rationale: The correct answer is Electromyography (EMG). EMG is commonly used to diagnose conditions involving muscle weakness and fatigue, such as myasthenia gravis. Nerve conduction studies primarily assess nerve function rather than muscle involvement. While a muscle biopsy can provide valuable information, EMG is more specific for evaluating muscle function in this context. A blood test for autoantibodies may be helpful in certain autoimmune conditions but is not the primary test for confirming the diagnosis based on the patient's symptoms of muscle weakness and fatigue.