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Delays in separating serum/plasma from cells allow ongoing cellular metabolism and membrane disruptions to alter analyte concentrations. For potassium, red cells and platelets contain higher intracellular levels; with prolonged contact, potassium diffuses into plasma/serum, artifactually elevating the result (pseudohyperkalemia). Additionally, glycolysis continues, altering pH and potentially shifting potassium distribution. Thus, Option C is correct. Laboratories typically recommend prompt centrifugation and separation—often within 1 hour (sooner in critical care). Option A is the opposite of what occurs for potassium; decreased values are more typical of analytes like glucose without glycolysis inhibition. Option B understates preanalytical instability. Option D is unsafe; effects are not self-canceling and can be clinically significant, prompting unnecessary treatment. Prevention includes timely transport, prioritizing STAT or urgent specimens, using appropriate tube types, avoiding hemolysis, and documenting collection and processing times. Understanding time-dependent changes is a central preanalytical competency tested across phlebotomy certifications.