Vertebrates that live in water and on land, smooth skin covers body, lay eggs, cold blooded.

• A. Amphibians
• B. Birds
• C. Fish
• D. Reptiles

Answer: (A)

Amphibians fit this description because they are vertebrates that live both in water and on land, have smooth, moist skin, lay eggs, and are cold-blooded. Their moist skin is a hallmark feature, helping with gas exchange and requiring a damp environment, unlike the dry, scaly skin of reptiles or the feathers of birds. Most amphibians start life in water, laying eggs in ponds or streams; these eggs hatch into aquatic larvae (like tadpoles) that later metamorphose into land-dwelling adults. Their body temperature mirrors the surroundings, not a constant internal temperature like birds or mammals. The combination of dual habitat, moist skin, aquatic eggs, and ectothermy makes amphibians the best match for this description.