Question

The presence of feathers and power of flight are the characteristic features of____________.
A. Mammals
B. Reptiles
C. Aves
D. Amphibians

Answer 1

As we know feathers are seen only in birds. Feathers are thought to provide flight as well as insulation also. However, since remains of feathers have been discovered in non-flying dinosaurs, the functions of feathers include both waterproofing and even thermoregulation also.

Complete answer:
Birds or Aves are the vertebrates that are characterized by feathers, beak and wings. Their forelimbs are modified into wings which are covered with feathers along with the rest of their bodies. Their wings help them to fly, which is their primary mode of locomotion.
Unlike aves, bodies of mammals are covered with hair and do not have a beak. They give birth to young ones and there is presence of mammary glands.
Reptiles were the first class of organisms to adapt to life on the land. They are believed to have evolved from the amphibians. They are cold-blooded animals which belong to the phylum Chordata of the Animal kingdom. These are creeping and burrowing terrestrial animals with presence of scales on their body.
Amphibians can live both on land and also in water. They are ectothermic animals, which are found in warm environments. Their body is divided into head and trunk. The tail may or may not be present. The skin is considered to be smooth and rough without any presence of scales, but with glands that make it moist. They have no paired fins, unpaired fins might be present.

So, the correct answer is option C which is 'Aves'.

Note:
Feathers are evolved from reptilian scales, where the scales in the ancestors of birds frayed and spilt, eventually turning them into feathers. If the reptilian scales were longer, it would have provided more lift, which enables the organism to glide further and farther. Later, these arms would have evolved into wings helping them in transitioning from gliding to true powered flights. Feathers in modern birds are brightly colored, this is in response to sexual selection.