Narrative:
In 1935, insect pests were destroying the sugarcane fields of Australia. Scientists brought in giant cane toads, which had voracious appetites, to eat the pests. Unfortunately, the cane toads were not interested in eating the field pests. Even worse, the toads themselves were toxic to predators. As a result, populations of birds and lizards that hunted the cane toads begin sharply decreasing. Cane toad populations exploded.

Which conclusion can you draw from the paragraph?


Scientists should have known that the toads would be a nuisance.

Nonnative species are always harmful.

Another species will need to be introduced to control the cane toad populations.

Nonnative species often lack natural controls found in their native habitat.

Native species cannot compete with nonnative species.