Sexual reproduction by protozoa is most likely conducted by conjugation fission meiosis

Option A, Conjugation

Explanation:

In the process of conjugation, two organisms of the same species forms a temporary association in order to exchange their nuclear material, or transfer their content completely to other or they fuse into one single organism.  

In case of ciliated protozoa, sexual reproduction takes place through conjugation. The two compatible mating strains only can reproduce through conjugation which means a protozoan can mate with a bacteria, algae or fungi  

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.

c is the correct answer hope this !