Final answer:
EDTA is an anticoagulant best used for Complete blood count (CBC) tests because it prevents clotting without destroying blood cells, which is crucial for accurate cell counting.
Step-by-step explanation:
The anticoagulant EDTA is most appropriate for a blood specimen that has been collected for Complete blood count testing (D). EDTA, or ethylenediaminetetraacetic acid, is widely used in blood collection tubes to bind calcium and prevent the blood from clotting. This is necessary for complete blood count tests, as the blood cells need to be intact for accurate counting and analysis. Other types of tests, such as blood glucose testing, may use different anticoagulants or none at all, depending on whether plasma or serum is needed. Hemoglobin testing can be performed with EDTA-anticoagulated blood, but it is not as specifically tied to the use of EDTA as complete blood count testing is. Blood cultures typically require a medium that supports the growth of microorganisms and therefore would not use EDTA, as it may inhibit their growth.