A class of animals known as Marsupials is a characteristic feature of

Answer: (b) Australia

Australia (with New Guinea) is the home of most marsupials — kangaroos, koalas, wombats.

The idea

Mammals bear their young in three ways. Monotremes lay eggs. Marsupials give birth to a tiny, unfinished baby that completes its growth in the mother’s pouch. Placental mammals keep the baby in the womb until it is well developed.

Baby is born after a few weeks, the size of a bean → Crawls through the mother’s fur → Enters the pouch → Fixes itself to a teat → Grows there for months

Why the others are wrong

(c) South America has opossums, but marsupials are the defining feature of Australia.

The trap

South America does have marsupials, so it is not wrong — just not characteristic.

Also know

Australian marsupials: kangaroo, wallaby, koala, wombat, Tasmanian devil. The word comes from the Latin for pouch.