Final answer:
The vacutainer with a purple or lavender top (option b) is most suitable for collecting blood for hematology tests because it contains EDTA, an anticoagulant that preserves blood cell shape and prevents clotting.
Step-by-step explanation:
The vacutainer most suitable for collection of blood for hematology is the one with a purple or lavender top. These tubes contain an anticoagulant called EDTA (ethylene diamine tetraacetic acid) that preserves the shape of blood cells and prevents clotting, making it ideal for hematology tests, where whole blood analysis is necessary, including cell counts and blood typing. The EDTA binds to calcium in the blood, thus preventing the coagulation cascade which is calcium-dependent.
For example, when a blood sample is taken from a patient with hemolytic anemia, it is crucial to prevent the blood from clotting to accurately measure parameters such as red blood cell count and the presence of antibodies. Moreover, in procedures such as cross-matching or typing, where the blood is tested for compatibility with potential donors or for determining one's own blood type, anticoagulated blood must be used to prevent clotting during the testing process.