Answer:
[a] varies in its characteristics according to local environmental circumstances
[b] becomes common within a species through natural selection
[d] tends to promote the well being of an organism in its natural or social environment
Explanation:
The adaptive traits in the living organisms have a simple basic role, that is to make the organism better suited for survival in its environment. The adaptive traits come in all sorts of different shapes, be it some that are manifested in the physical appearance or in the behavior of the organisms. Adaptive traits can be increased speed, prolonged neck, living in a groups, developing thorns and many more. This type of traits occur when the organisms face increased competition or when the environment in which they live starts to change, so in order for them to survive, they start to develop traits that will make them better suited for the new conditions and more competitive. The main principle through which the adaptive traits are transferred and rapidly increase in a population is through natural selection, as the organisms choose the ones that have advantageous traits for their mates, while they live aside the others.
Wind erosion is the main cause. And since it is the desert that wind can pick up tiny sand rock particles that slowly grind against the rock. Over time the erosion will give a jagged rock the smooth features as if it had been submerged in a river for the roughly same period of time.
