The correct answer is A metamorphosis and B lungs.
Amphibians develop special adaptation by which they are compatible of living both on land and in water.
The animals that live on land needs lungs to respire and the animals that live in water needs gills to respire.
The amphibians live in water in the starting days of their life as they have gills later they undergo through metamorphosis in which there is a development of lungs to live on land.