Correct Answer  Option 2 : 625 × 10
16
Concept:
Electric Current (I):
 It is defined as the net amount of electric charge that flows through a crosssection of a conductor in an electric circuit in a per unit time.

S.I unit of electric current is Ampere(A).
1 Coulomb (C):
 One Coulomb of charge is equal to the charge transported by an electric current of constant magnitude in one second of time.
 It is defined as the product of a 6.24 × 1018 charge of an electron.
 It is the S.I unit of electric charge.
Charge of one electron = 1.6 × 1019 Coulomb.
Explanation:
We know that e = 1.6 × 1019 C, i.e charge on the electron.
The total charge required is 1 Coulomb, q = 1C
Therefore we also know that q = n × e, (n = number of electrons on the charge)
Hence, n = q/e....(1)
Substituting all the values in the equation (1)
n = 1/1.6 × 1019 = 625 × 1016
So, if 1A current flows through the conductor then 625 × 1016 electrons flow per second across the crosssection of the conductor.