Question

Development of which trait freed land vertebrates from water

Answer 1

Trait
Trait is an inherited character and its detectable variant. For example, the tall and dwarf variant of stem height in plants.

Land vertebrates
Vertebrates (with a back bone made up of vertebrae) that live on land are called land vertebrates or terrestrial vertebrates. Examples include reptiles and birds.

Four appendages
Four appendages (two fore limbs and 2 hind limbs) is the trait found in almost all vertebrates. It is not the trait which freed land vertebrates to evolve from water.

Four chambered heart
Four chambered heart (two auricles and two ventricles) is a specific characteristic of birds, mammals and crocodiles. All the terrestrial vertebrates do not have a four-chambered trait.

Cleidoic eggs
Eggs surrounded by a hard protective shell are known as cleidoic eggs.This shell protects the egg from desiccation. Terrestrial vertebrates like reptiles and birds lay cleidoic eggs. The development of cleidoic eggs freed land vertebrates from water.

Lungs
Lungs are the respiratory organs. It is not the active respiratory organ always in all terrestrial vertebrates. For example, in frogs, skin, lungs and the lining of the mouth act as respiratory organs.

Final answer
(C) Cleidoic egg