it's D but I might be wrong
All three are bad for the environment because all three types release CO2 into the air and have throughout their constant usage helped with creating the greenhouse effect that traps heat and causes global warming. That's why clean energy is a necessity and people are developing harnessing wind and solar power.
A) a common ancestor
Homologous structures are structures that are similar in related organisms. There is a basic pattern of bones which can be inherited from a common ancestor
