Which of the following is not a reason that cane toads became an invasive species in australia?
a. they are poisonous to most animals.
b. they are voracious predators.
c. they have almost no natural predators.
d. they are not well adapted to the australian climate.

d.

They are not well adapted to the Australian climate.

Option D, They are not well adapted to the Australian climate.

Explanation:

Cane toads in Australia have a deadly chemical defense system due to which these toads are poisonous for most of the animals.

These were introduced in Australia as a process of controlling the pests i.e  Australia's sugar cane-ravaging beetles but instead they themselves became the pest.

They have high productivity due to high healthy sex drive which makes them voracious predators.

These facts shows that cane toads have very well adapted themselves to the Australian climate.

Hence, option D is the correct answer