Which example below is a current hypothesis regarding the Cambrian explosion?
A. An increase in atmospheric CO₂ led to an explosion of plants and life forms that fed on plants.
B. Predator-prey relationships decreased diversity through natural selection.
C. A rise in atmospheric nitrogen led to the success of large animals with higher metabolic rates.
D. Evolution of the Hox gene complex provided developmental flexibility.
E. All of the above.
