You are evaluating a trial where the enrolled participants are all sedentary obese adults aged 50–70 with metabolic syndrome, and the trial tested a Mediterranean-style diet. How would you apply the generalizability checklist for a 28-year-old active athlete with normal BMI seeking performance nutrition advice?

• A. Conclude high generalizability because dietary principles are universal across ages and activity levels, so the trial supports immediate adoption for athletic performance.
• B. Apply the diet without modification because disease-focused trials always improve athletic performance irrespective of baseline health.
• C. Assume the trial invalidates the Mediterranean diet for everyone because it targeted older adults, so younger athletes should avoid it.
• D. Conclude low direct generalizability: the trial population differs markedly (older, sedentary, metabolically unhealthy) from the younger active athlete, so the intervention's clinical effects may not translate to performance nutrition goals without additional athlete-specific evidence.

Answer: (D)