Tissues
Tissues are somewhat more complex units than cells. By definition, a tissue is an organization of a great many similar cells with varying amounts and kinds of nonliving, intercellular substance between them.
A cow will eat grass in a field, the grass is the plant and the plant eater is the cow. (Srry if this is not what your looking for)
C. the crust and upper mantle
There is no pigment in the brain, so it is in it's natural colour, grey.
