Cladistics is a classification system based on a. nomenclature
b. dichotomous keys
c. common ancestry
d. physical characteristics

c

Explanation:

cladistics is based on evolutionary ancestry and generates trees called cladograms. Cladistics also identifies clades, which are groups of organisms that include an ancestor species and its descendants. Classifying organisms on the basis of descent from a common ancestor is called phylogenetic classification.

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.

satellites are frequently used to make observations of the orbit on earth