Answer:
A: Example
Explanation:
The passage hints at the meaning of the word MARSUPIAL using an example, listing kangaroos, koalas and wallabies as this example.
A marsupial is an animal that carries its young in a pouch on its belly, and it is commonly known that kangaroos/koalas/wallabies do this.
Therefore, the answer is A - the passage used an example as a clue to the meaning of the word marsupial.
