In the Figure,when the Terminal Voltage V_ab of the Battery

In the figure,when the terminal voltage V_ab of the battery is equal to 20 V,how much current passes through the battery,including its direction?

A) 4 A,from a to b
B) 5 A,from a to b
C) 6 A,from a to b
D) 4 A,from b to a
E) 5 A,from b to a