Question

Orchids, ferns, fruit trees, parrots, and frogs are just some of the thousands of species that can be found in Australia’s __________ ecosystem. A. desert B. grassland C. marine D. rainforest

Answer 1

D. Rain-forest, because all those things you listed cannot be found in a dessert or underwater. And grassland doesn't have enough places for a frog to hide and enough moisture for ferns to grow. 

Answer 2

I would say the answer is - D. rain forest

Hope that helps :P<span />