Division of WBC takes place by

The correct answer is None of the above.

To understand why this is the correct choice, let us examine the nature and life cycle of white blood cells (WBCs), also known as leukocytes:

1. Mature WBCs do not divide:
Fully formed, mature white blood cells circulating in the bloodstream are specialized, terminally differentiated cells. Most of them (such as granulocytes) have a short lifespan and do not undergo cell division (mitosis, amitosis, or meiosis) to replicate themselves in circulation.

2. Origin and Production (Hematopoiesis):
New white blood cells are continuously produced from multipotent hematopoietic stem cells located in the bone marrow (and sometimes lymphoid tissues), rather than through the division of existing mature WBCs.

3. Evaluation of the Options:
• Mitosis: While the precursor stem cells in the bone marrow undergo mitosis to differentiate into various WBC lineages, mature circulating WBCs themselves do not divide by mitosis.
• Meiosis: Meiosis is a specialized form of cell division that occurs only in germ cells to produce gametes (sperm and egg cells). It is not involved in the division or production of somatic cells like WBCs.
• Amitosis: Amitosis is a direct cell division method (without spindle formation or chromosome condensation) occurring mainly in unicellular organisms or specialized tissues, and is not the method of division for WBCs.

Therefore, since mature white blood cells in circulation do not undergo division by any of these methods, the correct choice is None of the above.