Mesoderm
Mesoderm is the primary germ layer that is responsible for producing both blood and phagocytic brain glial cells.
The mesoderm is the middle of the three germ layers that appears in the third week of embryonic development. The mesoderm is responsible for the formation of various body structures such as epithelia of blood vessels, blood, muscle, bone, phagocytic brain glial cells, lymphatic vessels, adrenal cortex, notochord, and bone marrow.
I believe the answer is B - point source comes from a specific site, non-point comes from many sources
convergent evolution - called analogy
a potential source of confusion in constructing a phylogeny is similarity between organisms that is due to convergent evolution - called analogy - rather than to shared ancestry. thus for mammals, the backbone is a shared ancestral character, a character that originated in an ancestor of the taxon
