Which cellular adaptation would occur in a client who has enlargement of the cells in the heart due to heart failure?

Choice A reason: Facial trauma may increase aspiration risk if swallowing is impaired, but a 21-year-old typically has a robust immune system, reducing pneumonia risk. The trauma does not directly compromise lung defenses or immune function significantly, making this individual less likely to develop pneumonia compared to an immunocompromised person.

Choice B reason: Osteoarthritis and chronic knee pain in a 72-year-old may limit mobility, slightly increasing pneumonia risk due to reduced lung expansion. However, this condition does not directly impair immune function or lung clearance mechanisms, making it a lower risk compared to immunodeficiency, which severely predisposes to infections.

Choice C reason: Elevated cholesterol in a 48-year-old increases cardiovascular risk but does not directly affect lung function or immune response to infections. Without respiratory or immune compromise, this individual has a lower risk of pneumonia compared to someone with a primary immunodeficiency disorder, making this choice incorrect.

Choice D reason: A 69-year-old with a primary immunodeficiency disorder has a severely compromised immune system, impairing the ability to fight respiratory infections like pneumonia. Age-related lung changes and reduced immune response increase susceptibility to pathogens, making this individual at the highest risk for developing pneumonia, which is why this is correct.

Choice A reason: Autosomal dominant disorders affect both genders equally, as they are not sex-linked. Heterozygous individuals express the disorder, not just males, due to the dominant allele on an autosome. The idea of females being carriers only applies to X-linked recessive disorders, making this choice scientifically inaccurate.

Choice B reason: Autosomal dominant disorders are caused by mutations on autosomes, not the Y chromosome, which is sex-linked and primarily affects males. These disorders do not typically skip generations, as the dominant allele is expressed in every affected individual, making this choice incorrect.

Choice C reason: In autosomal dominant disorders, a single mutated allele is sufficient for expression. An affected parent (heterozygous) has one normal and one mutated allele, leading to a 50% chance of passing the mutated allele to each child, causing the disorder. This genetic inheritance pattern makes this the correct choice.

Choice D reason: In autosomal dominant disorders, there is no "carrier" state as in recessive disorders, because heterozygous individuals express the disorder. The 50% probability applies to inheriting the disorder itself, not a carrier genotype, which is a concept relevant to autosomal recessive disorders, making this choice incorrect.