When we talk about evolution we come across the process of natural selection. Genetic variation is always required for the natural selection. A change or variation in the genes may help the individuals in a population to better adapt to the environment. Such changes may be brought by mutations or random mating in the population. Such variations help in the survival of the population by allowing them to adapt to changing environmental conditions.
Answer: Primary Sex characters
Explanation:
The primary sexual characters are associated with the growth of sexual organs such as uterus, vagina, penis and other reproductive organs in the human beings.
These organs are present in the body when the child is borne. This is because they grow when the child is inside the womb.
The development and maturation of these organs takes place during the later stages of life.
C: lack of water during long periods..