Which of the following individuals would be at greatest risk of opportunistic infection?

A. To predict a prognosis: Predisposing factors can help estimate risk and influence prognosis, but prognosis also depends on disease stage and response to treatment - this is a useful but not the primary public-health focus.
B. To determine treatments: Knowing predisposing factors can guide individualized management (e.g., controlling diabetes reduces infection risk), but treatment decisions usually depend on current disease state as well.
C. To develop preventative measures: Identifying predisposing factors is fundamental for prevention (screening, lifestyle modification, vaccination, risk-reduction strategies) to reduce disease incidence.
D. To develop morbidity statistics: Predisposing-factor data contribute to epidemiology and morbidity statistics, but that is a secondary use compared with prevention.
E. To test new drug treatments: While epidemiologic knowledge can inform research priorities, testing new drugs is not the primary reason we identify predisposing factors.

A. increase in number: Cardiac myocytes in the adult are largely terminally differentiated, so they do not appreciably multiply (hyperplasia) in response to increased workload.
B. increase in excitability: Increased workload causes structural and functional adaptation (hypertrophy) rather than a primary increase in membrane excitability; excitability changes are more a feature of pathological electrical remodeling.
C. decrease in length: Cells do not shorten as an adaptive response to increased workload; they grow (change in size/shape) rather than decrease in length.
D. increase in size: Cardiac muscle responds to increased workload by hypertrophy (an increase in cell size) to generate greater contractile force.