During the cambrian period on earth, the layer developed along with the massive production of oxygen.
a) ozone
b) ocean
c) mantel
d) carbon dioxide

What's wrong with this ecological pyramid? (multiple choice)1. secondary consumers should be at the bottom of the pyramid2. the sun has an arrow leading to decomposers 3. primary consumers should come after the sun4. energy retained should increase from the bottom to the top5. the sun should be at the bottom of the pyramid