Below are the choices:
The climate cooled and many tropical areas experienced freezing temperatures for the first time.
Rainfall gradually diminished and areas that were once grassy and forested became deserts.
Volcanic activity turned much of the area into lava fields where few life-forms could survive.
Rainfall gradually increased and desert areas eventually became rain forests
The answer should be Rainfall gradually diminished and areas that were once grassy and forested became deserts.