The correct answer is option 3: Amphibians.

Amphibians are a group of animals that are adapted to both aquatic and terrestrial life. They have unique physiological and anatomical adaptations that allow them to live in both environments.

Option 1: Mammals - While some mammals, like seals and otters, are capable of living in the water, they are not as well-adapted to aquatic life as amphibians. Mammals generally have lungs for breathing and are better suited to terrestrial habitats.

Option 2: Birds - Birds are well-adapted for life in the air and on land, but they do not have the same level of adaptation for aquatic life as amphibians. They have feathers, which help them fly, but they do not typically possess the ability to live in water for extended periods.

Option 4: Reptiles - Reptiles, such as turtles and crocodiles, can live in water and on land, but they are not as well-adapted to aquatic environments as amphibians. Reptiles have lungs for breathing air and are mostly found in terrestrial habitats.

Overall, amphibians have specialized features like moist skin, gills for breathing underwater, and the ability to undergo metam