Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 21 to 25.

There are 4400 living species of amphibians. Frogs, toads, newts and salamanders are all amphibians. Many live mainly on land, but most spend at least some of their lives in water. The largest amphibian, the Chinese giant salamander, is 1.8m long.

Frogs and salamanders are able to breathe through their damp skins to a certain extent, both in the water and on the land, but toads rely largely on their lungs and cannot remain underwater for long. Toads and frogs are similar in many ways, although toads usually have rougher, drier skins and may waddle rather than hop as frogs do.

Some toads produce spawn in strings like necklaces, rather than the mass of eggs laid by frogs.

Most amphibians lay their eggs in water. Frogs’ eggs are called spawn. The eggs are protected from predators by a thick layer of jelly. A tadpole develops inside each egg. When it hatches, it is able to swim using its long tail, and it breathes through gills. As a tadpole grows, first hind legs then forelegs begin to form. Lungs develop, and the young frog is able to begin to breathe with its head above water. Gradually, the tail shortens until the young frog resembles its adult parents.

The text describes amphibians as animals that ________.