According to Hugo de Vries, mutations are ..........

'$A$ brief reduction in size of a population,due to natural calamities,usually leads to random genetic drift'. For this statement,identify the correct example from the following.

What do hummingbirds and hawks represent?

Which organisms are considered the most adapted in the environment?

The weakest point of Darwinism was that it could not explain which of the following?

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