Monotremes are mammals that reproduce by laying eggs.
Well, platypuses are mammals, and they lay eggs.
Platypuses are monotremes.
A platypus is an example of _.
Options:
1: Marsupial.
2: Monotremes.
3: insects
4: animals
5: killing insects
6: Amphibian.
7: Placental mammal.
8: matter vibrating