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OGTT accuracy depends on standardized physiologic conditions. Patients should maintain their usual carbohydrate intake for ~3 days prior, then fast 8–12 hours (water only) before the test. On arrival, a fasting specimen is collected, the glucose solution is consumed within ~5 minutes, and the patient remains seated and refrains from smoking, eating, or exercise until all subsequent timed draws are complete (e.g., 2-hour sample). Option B incorporates these requirements. Extended fasting and heavy exercise (Option A) can alter insulin sensitivity and skew results. Coffee (Option C)—especially with sugar/cream—breaks the fast and caffeine alone may affect glucose metabolism. Diuretics (Option D) are not used to “concentrate” glucose and can cause dehydration and orthostasis. The phlebotomist should verify fasting status, document exact collection times, and ensure timely processing (e.g., use fluoride/oxalate or rapid separation to mitigate glycolysis). Clear prep and timing minimize recollects and ensure results align with validated reference intervals—key exam competencies.