Correct Answer: B

Rationale: Acetylcholine acts as an inhibitory neurotransmitter at the sinoatrial node. It slows down the heart rate by decreasing the firing rate of the sinoatrial node, which serves as the heart's natural pacemaker. Neurotransmitters do not have a charge, so choice A is incorrect. Choice C is wrong as overstimulation is not a characteristic of acetylcholine at the sinoatrial node. Choice D is also incorrect because acetylcholine actively influences heart rate regulation when released at the sinoatrial node.

Correct Answer: A

Rationale: The correct answer is A. Finasteride, a type of androgen therapy, has been shown to reduce the risk of developing prostate cancer. It works by shrinking the prostate gland, which can help lower the risk of developing prostate cancer. However, while it may reduce the risk, regular screening is still recommended to monitor for any potential issues. Choice B is incorrect because finasteride does have an impact on reducing the risk of prostate cancer. Choice C is incorrect as finasteride is not known to increase the risk of developing prostate cancer. Choice D is incorrect as finasteride does have an effect on reducing the risk of prostate cancer.

Correct Answer: B

Rationale: The correct answer is B because hormone replacement therapy (HRT) is associated with an increased risk of cardiovascular events, including venous thromboembolism. Patients with a history of venous thromboembolism are at higher risk, so discussing this potential risk is crucial. Choice A, increased bone density, is not a major risk of HRT. Choice C, reduced risk of breast cancer, is not a common discussion point regarding HRT risks. Choice D, improved mood and energy levels, is more related to the benefits of HRT rather than its risks.

Correct Answer: C

Rationale: Ptosis (drooping eyelid) and diplopia (double vision) are classic symptoms of myasthenia gravis. Muscle atrophy (Choice A) is not a typical early manifestation of myasthenia gravis. While facial weakness (Choice B) can occur, it is not as specific as ptosis and diplopia. Increased muscle tone (Choice D) is more indicative of conditions like spasticity, not myasthenia gravis.

Correct Answer: A

Rationale: The correct answer is A: Jaundice. Fluconazole, an antifungal medication, can rarely cause hepatotoxicity, which may manifest as jaundice. Monitoring for signs of liver dysfunction, such as jaundice, is crucial during fluconazole therapy. Weight gain, iron deficiency anemia, and hematuria are not commonly associated with fluconazole use and are not indications for discontinuing the drug.