Which of the following tubes is used for hematologic testing?

The lavender stopper tube is designed specifically for hematologic testing, making it the correct choice for this question. This tube typically contains EDTA (ethylenediaminetetraacetic acid), an anticoagulant that prevents blood from clotting. By using EDTA, accurate results can be obtained for complete blood counts (CBC) and other hematological assessments, as the blood remains in a liquid state, allowing for the examination of cellular components such as red blood cells, white blood cells, and platelets.

Hematologic testing requires the preservation of blood cells in their natural state, and the use of the lavender stopper tube with EDTA ensures that cell morphology can be accurately evaluated, which is essential for diagnosing various hematologic disorders.