Explanation:
see the pic for the answer
I'm pretty sure it's A, but then again I'm only in 8th grade. Sorry if this doesn't help:(
The answer is (4). The same magnitude and the opposite sign. For a proton, it has one positive electric charge. And for electron, it has one negative electric charge. So they have same magnitude but opposite sign.
Decrease the temperature of the oxygen because if coal goes air born it can explode and wipe out power plants like they were not there