The change in environments that may have occurred at the end of the paleozoic era may have been caused by
a. mass extinctions
c. plate tectonics
b. evolution of the dinosaurs
d. the beginning of an ice age

Alrighty, so, I believe the answer you're looking for is C.) Plate tectonics. All of the continents used to be combined at one point, when they separated, everything changed because certain areas of land were then at different parts of the planet. Fossils have been discovered of certain dinosaurs that could never have lived in the climates in which they were found which furthers the plate tectonics theory.

The change in environments that may have occurred at the end of the Paleozoic Era may have been caused by plate tectonics.

Hope this helps!