Retina and start of optic nerve
Fires that clear forest creates large amounts of smoke when wood is burned, while deforestation is where wood is just cut and used for supplies which also generates smoke from all the machinery, but it's not as much as fire creates. Both are bad but in my opinion fire is worse.
Build up of FRICTION has been used to try to predict earthquakes, should be the write answer.
One of them i think is biolorgy with 5th and 6th