Apopulation is defined as…
a. a group of non-randomly mating organisms.
b. a group of subspecies inhabiting several regions.
c. a group of individuals of the same species inhabiting a defined area.
d. a group of individuals reproductively isolated from other such groups.

C) a group of individuals of the same species inhabiting a defined area.

Explanation:

Population is defined as a group of individual o the same species occur together in any particular place and time. Different organisation are examined by the different organisms. Population refers to the group of individual and a small group of tribe which commonly sharing specific environment. A group of multiple population are interacted to formed meta population.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added