Correct Answer: C

Rationale: The correct answer is C: 'It is usually triggered when the patient bends forward.' Benign positional vertigo is often triggered by changes in head position, such as bending forward. Choices A, B, and D are incorrect. A is incorrect because benign positional vertigo is not typically associated with headaches. B is incorrect because pupillary changes are not a common feature of benign positional vertigo. D is incorrect because nystagmus in benign positional vertigo usually stops when the eyes fixate on an object.

Correct Answer: A

Rationale: The correct answer is A: live and can cause infection. In patients like the one described with a history of heart transplant and receiving long-term steroids, who are immunocompromised, live attenuated vaccines are contraindicated. Live vaccines contain weakened (attenuated) forms of the virus or bacteria, which can replicate and cause mild infections in healthy individuals but can lead to serious infections in immunocompromised individuals. Choices B, C, and D are incorrect because attenuated vaccines are not mutated, not inactive, and not pathogenic in healthy individuals, respectively.

Correct Answer: B

Rationale: The correct answer is B: Underexcretion of uric acid. Gouty arthritis is primarily caused by the underexcretion of uric acid, leading to its accumulation in joints and subsequent crystallization. Choices A, C, and D are incorrect as they do not directly relate to the pathophysiology of gout. Destruction of proteoglycans, overexcretion of uric acid, and increased absorption of uric acid are not primary causes of gouty arthritis.

Correct Answer: B

Rationale: Bullous impetigo is the correct answer because it is caused by a Staphylococcus aureus toxin that leads to exfoliation and the formation of large blisters. Herpes simplex I virus (Choice A) causes cold sores and is not associated with exfoliation and blister formation. Necrotizing fasciitis (Choice C) is a severe skin infection involving the deeper layers of skin and subcutaneous tissues, typically caused by bacteria such as Streptococcus or Clostridium species, not Staphylococcus aureus. Cellulitis (Choice D) is a common bacterial skin infection, but it does not involve exfoliation and blister formation as seen in bullous impetigo.

Correct Answer: B

Rationale: The correct answer is B. Morbid obesity increases the risk of dehydration due to the larger body surface area and potential for greater insensible losses. Choices A, C, and D are less likely to experience dehydration compared to a morbidly obese individual.