Answer:
Natural selection is the process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. ... Individuals with adaptive traits—traits that give them some advantage—are more likely to survive and reproduce.
Fresh water is any body of water with a low salt concentration. Organisms in fresh water various challenges which includes; Osmotic concentration such that fresh water is permanently dilute and most cells cannot function at this concentration of ions. Varying temperatures, variation in oxygen levels and reproduction and life cycle due to permanence of habitat and physiological difficulty of regulating osmotic concentration in larvae and juveniles.
it separates the inside of the cell from the environment outside and it controls substances moving in and out of the cell (selectively permeable)
Both answers C and D are correct, however, answer D makes more sense.
The answer is the first one: “...attract each other.”
