The large rounded brain near the center of the cell is the

The large rounded brain near the center of the cell is the nucleus. It is known as the brain because it is responsible for most of the cell functions. Similarly to the human brain, the nucleus sends information and instructions to the cell.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

i think its both a and b