Why do adaptations occur?

Genetic drift operates only in

'Population tends to increase geometrically,while food supply increases arithmetically'. This concept was put forward by

According to Hugo De Vries, speciation is due to

Evolution is a process or the result of a process. Explain this statement.

Assertion : Natural selection is the outcome of difference in survival and reproduction among individuals that show variation in one or more traits.
Reason : Adaptive forms of a given trait tend to become more common; less adaptive ones become less common or disappear.