Answer:
The humans use this limb to grab things, body language, and sign language.
The dogs use this limb for all kinds of weight-bearing activities like walking, jumping, running et cetera.
Birds use this to fly and whales use it as flapper.
The limbs of all these four animals are the example of homologous organs that is, they all are similar in structure but adapted to perform different functions during the course of evolution.
For example, in all four organisms, the limb is made up of the same set of bones such as humerus, radius, ulna, carpals, metacarpals, and phalanges.
Homology in structure shows that they must have evolved from a common ancestor and diverge to perform different functions as an adaptation to the contrasting environment.