Final answer:
The lavender-topped tube contains the anticoagulant EDTA, which is used to preserve blood cells and prevent clotting for hematological tests.
Step-by-step explanation:
The tube that contains the additive EDTA is the lavender-topped tube. EDTA (ethylene diamine tetra-acetic acid) is a common anticoagulant used in phlebotomy to prevent coagulation, and these tubes are frequently used to collect blood samples for complete blood counts (CBC) and other hematological tests. When blood is collected into EDTA tubes, it is often centrifuged to obtain plasma for various diagnostic tests. The inclusion of the chelating agent EDTA helps preserve blood cells and prevent the blood from clotting, which is necessary for accurate and reliable results.