Which of the following types of isolation is important for speciation?

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.

Which one of the following was the contribution of Hugo de Vries?

$A$: $A$ single large mutation called saltation can produce new species.
$R$: Mutations are directional.

Who proposed the theory of continuity of germplasm?

As a result of the excessive use of herbicides and pesticides,which types of varieties were selected in a short period?