Correct Answer: A

Rationale: The correct answer is A: live and can cause infection. Patients who are immunocompromised, like those receiving long-term steroids after an organ transplant, should not receive live vaccines because the live attenuated organisms in these vaccines can cause infections in individuals with weakened immune systems. Choice B is incorrect because attenuated vaccines are live but weakened, not mutated. Choice C is incorrect because while inactive, attenuated vaccines are not infectious. Choice D is incorrect because attenuated vaccines are not pathogenic; they are attenuated (weakened) forms of the pathogen.

Correct Answer: C

Rationale: The symptoms described in the scenario, such as visual hallucinations, fluctuations in cognition, and parkinsonism (bradykinesia and limb rigidity), are classic features of dementia with Lewy bodies (DLB). DLB is characterized by the presence of Lewy bodies in the brain, which are abnormal protein deposits. Alzheimer's disease (Choice A) typically presents with memory loss as a predominant symptom, which is not a major concern in this case. Vascular dementia (Choice B) is associated with a history of cerebrovascular disease and is not supported by the symptoms described. Frontotemporal dementia (Choice D) usually presents with changes in behavior and personality, rather than the symptoms described in the scenario.

Correct Answer: D

Rationale: The correct answer is Hemangiomas, congenital dermal melanocytosis (i.e., Mongolian spots), and macular stains. These three types of birthmarks are known to fade or regress as the child gets older. Hemangiomas are vascular birthmarks that often shrink and disappear over time. Congenital dermal melanocytosis, commonly known as Mongolian spots, usually fade by adolescence. Macular stains, also called salmon patches, tend to lighten and fade as a child grows. The other choices are incorrect because they do not typically fade or regress with age.

Correct Answer: B

Rationale: In this scenario, the rising lactic acid levels in a 65-year-old man after a coronary artery bypass graft could indicate bowel ischemia. Bowel ischemia can lead to anaerobic metabolism, causing an increase in lactic acid levels. Excessive sedation may cause respiratory depression but would not directly lead to rising lactic acid levels. Excessive volume infusion in the operating room might cause fluid overload but would not typically result in rising lactic acid levels. Mild hypothermia postoperatively could lead to shivering and increased oxygen consumption, but it is less likely to be the primary cause of rising lactic acid levels in this context.

Correct Answer: B

Rationale: Muscular dystrophy is primarily caused by mutations in the gene that provides instructions for making the protein dystrophin. Dystrophin plays a crucial role in maintaining the structure of muscle fibers. Glycoprotein is a general term for proteins with sugar molecules attached, not specifically related to muscular dystrophy. Troponin is a protein involved in muscle contraction regulation, and actinomyosin is not a specific muscle protein but a complex formed during muscle contraction. Therefore, the correct answer is dystrophin.