Ecology
is made up of the science of biology. Ecology is a science that deals with the
relationships between groups of living things and their environments. To exist
with one another, organisms belonging to a same species either compete for the
resources or divide it amongst themselves, where animals and plants of the same
species co-exist and creates a beauty with nature.
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The answer is a because it just is
Valence shell
The number of electrons in the outermost shell of a particular atom determines its reactivity, or tendency to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons.
The typical cell types found in connective tissue: fibroblast Mast cells plasma cells macrophages, adipocytes leukocytes
I think c and d is the best answers