Answer:
Earthquakes and volcanoes
Explanation:
Earthquakes are caused by any type of plate movement in response to the plates reacting to one another in some way.
Volcanoes can be caused when there is a plate being sucked under another plate causing magma to rise up and eventually errupt.
The position of the sun in the sky
I know jobs for one, over population maybe, and because they are worried that dangerous people could be entering into the country with intention to harm. (unless this is a "only 3 right answer" kind of thing)
I think that a) is chemical, and b) would be chemical
