Final answer:
The tube with lithium heparin contains the anticoagulant heparin. Lithium heparin prevents blood from clotting in the tube and is commonly used for plasma collection and analysis.
Step-by-step explanation:
The tube that contains the anticoagulant heparin is the tube with lithium heparin. Heparin is an anticoagulant substance that opposes coagulation. In this case, it is mixed with lithium to prevent blood from clotting in the tube. Lithium heparin is commonly used for plasma collection and analysis.