Answer:
The correct answer is : A. red stopper tubes.
Step-by-step explanation:
In phlebotomy the red stopper tubes are plastic tubes or container that have a clot forming or clot activator in It instead of anticoagulants, preservatives or material that prevent blood to mix like other blood tubes.
Lavender, purple, light blue or green all have anticoagulant or preservative in them to prevent from clotting the blood. This tube is used for taking serum sample in it for test.
Thus, The correct answer is : A. red stopper tubes.