Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Environmental changes is most responsible for the extinction of most species of plants and animals that have lived on earth.
What process is most responsible for the extinction of most species of plants and animals that have lived on Earth?

The main advantage of urea is its very low toxicity.
The main advantage of urea is its very low what?

Ectothermic vertebrates control body temperature to just a limited extent from the outside by changing behavior.
What type of vertebrates control body temperature to just a limited extent from the outside by changing behavior?