Question

The development of____ factored into the development of complex organisms.

Ozone
Oxygen
Cyanobacteria
All of the above

The end of the Paleozoic Era was signaled by____.

The development of humans
Mass extinction of land and sea animals
The development of organisms with hard parts
Both a and b

Reptiles evolved from an ancestor of amphibians that developed a(n)____.

Egg with a strong outer shell that kept it from drying out
Hard set of teeth
Thick eyelid
Long tail

Answer 1

@green_1
@ghostgate
@miracrown
@nnesha
@sweetburger
@zepdrix

Answer 2

1)ozone, oxygen, and cyanobacteria
2) mass extinction....
3) egg with a strong outer shell that kept it from drying out @nightcore144

Answer 3

thank you @Koikkara