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Whole-blood citrate specimens for coagulation testing are typically maintained at room temperature and analyzed within the laboratory’s validated window (commonly ≤4 hours for PT and shorter for some aPTT methods) unless plasma is separated and frozen per policy. Refrigeration or chilling whole blood can induce cold activation of platelets and factor changes (e.g., von Willebrand factor/platelet activation) that artifactually alter clot times. Therefore, do NOT place unprocessed citrate tubes on ice or in the refrigerator. Mix by gentle inversion at collection, transport promptly upright, and avoid excessive agitation. If delays are unavoidable, coordinate with the lab to prepare platelet-poor plasma and freeze according to guidelines. Option B reflects these principles. Options A, C, and D risk preanalytical alteration of coagulation factors. Adhering to tube fill (9:1 ratio), avoidance of hemolysis, and timely processing preserves result integrity—a common certification topic.