Final answer:
Option (B), The preferred tube type for collecting blood for a manual WBC differential is the lavender top tube, which contains EDTA to prevent clotting and preserve cell shape for accurate analysis.
Step-by-step explanation:
When collecting blood to perform a manual WBC differential, the preferred type of blood tube is B. Lavender top. These tubes contain EDTA, which is an anticoagulant that helps preserve the shape of cells and prevents clotting. Using lavender top tubes is crucial for obtaining an accurate differential white blood cell count, as the proper staining and identification of white blood cells depend on the cells being intact and not clotted.
During a differential cell count, the technologist makes a blood smear, often using Wright-Giemsa stain. This process is used to prepare slides for microscopy, where various types of white blood cells are examined and counted based on their appearances, which are highlighted by the stain.