Concept:
Human blood consists of cellular components suspended in plasma. The three main types of blood cells are Red Blood Cells (RBCs), White Blood Cells (WBCs), and platelets. Their relative abundances differ significantly.
Step 1:Comparing the abundance of blood cells.}
In a healthy adult, the approximate counts per microliter of blood are:
- RBCs (Red Blood Cells): 4.5–5.5 million
- Platelets: 1.5–4 lakh (150,000–400,000)
- WBCs (White Blood Cells): 4,000–11,000
- Plasma cells: Very rare (present mainly in bone marrow and lymphoid tissues, not circulating in significant numbers)
Step 2:Evaluating each option.}
- (A) WBCs: Only 4,000–11,000 per microliter. Far less abundant than RBCs.
- (B) RBCs: Approximately 4.5–5.5 million per microliter. These are the most abundant blood cells by a large margin.
- (C) Platelets: 1.5–4 lakh per microliter. More abundant than WBCs but still much less than RBCs.
- (D) Plasma cells: These are antibody-producing cells derived from B-lymphocytes. They are not typically found circulating in blood; they reside in bone marrow and lymph nodes. Their numbers are negligible in blood.
Step 3:Conclusion.}
Red Blood Cells (RBCs) outnumber all other blood cells combined. They constitute about 99% of all blood cells. Therefore, the correct answer is (B) RBCs.