Cacti in the deserts of southwestern North America and some euphorbs (succulent plants) of the deserts of Africa, have barrel-shaped stems, short-lived leaves, and spines, yet these two types of plants are from different evolutionary lineages. This is an example of A. selective breeding. B. transitional forms. C. homologous traits. D. convergent evolution. E. concave evolution

D. convergent evolution

Explanation:

Cacti or cactuses are member of the plant family and are often referred to as spiny plants that are usually found in the desserts.

Evolution - In biology, is described the ascent or descent in the characteristics of a species over a series of generations

and natural selection favors its modification.

When two species populations evolve to become more similar to each other we say say they have a convergence evolution.

Hint: Evolution of analogous structures is always an example of convergent evolution.

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.

the answer is:

carbon dioxide