Birds fly with the help of
A)Patagium
B)Wing
C)Feather
D)Limbs

Hint: The primary mode of locomotion of the birds is flight. The bones of the birds are light and hollow which helps them for flying. The birds flap their wings for flight.

Complete answer:
The birds belong to the family of Aves. The birds fly with the help of wings. The structure helps in propelling the birds in air. The wings are the modification of forelimbs. The forelimbs are the main organ for flight. The wings are composed of three limb bones-the humerus, ulna and radius. The carpus and metacarpus form the wrist and the digits are fused together.

Adaptations of birds for flight-
1)Streamlined body
2)Bones are hollow, strong and light.
3)Body covered with feathers which indirectly help in flight.
4)The tail helps in balancing.
5)The birds have large chest muscles to help moving wings.

Patagium- It is a membranous structure which helps the animal in flight. It is mostly found in extinct species like flying frogs, flying lizards, gliding mammals like bats.
Feather- The body of the birds is covered with feathers which indirectly help in flight and also protects the body and provides insulation.
Limbs- The forelimbs are modified into wings and the hindlimbs are modified for walking, swimming.

Hence, the correct answer is option (B)

Note: The wings of birds, arms of humans and the forelimbs of horses are homologous structures. They are similar in structure but differ in function. The wings of birds and bats are analogous. They differ in structure but perform the similar function of flight.