Its an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell.
I think it's A) Sunspots. I hope this helps:)
Explanation:
When one coulomb charge passes through any cross section of the wire per second,the current passing is one ampere. Charge of electron ,e=1.6X10^-19C. n=1/(1.6X10^-19)=6.25X10^18.Sep 17, 2017