Answer:
c) Habitat isolation
Explanation:
Habitat isolation is a mechanism that prevents species from mating even if they don't have reproductive barriers. The differences in the habitat types may thus be sufficient to develop reproductive isolation between two (or more) populations
Circulatory system.....circulates blood (a vital delivery system of oxygen) throughout the whole body when tissues need it the most and with a constant supply.
Bacteria cells, I believe so.
A) The earth spins
The Earth is constantly spinning, or "rotating", which causes day and night
