In a Certain Material There Is a Current of 18

Multiple Choice

In a certain material there is a current of 18 A flowing through a surface to the right,and there is an equal amount of positive and negative charge passing through the surface producing the current.How much negative charge passes through the surface?

A) 9 C/s toward the right
B) 9 C/s toward the left
C) 18 C/s toward the right
D) 18 C/s toward the left
E) 36 C/s toward the left