A graph of the current I in an RC circuit during the discharge of a fully charged capacitor is a smooth curve that starts at I=I0 when t=0 and approaches zero as t increases. Which statement best describes the simultaneous graph of the voltage V across the capacitor?
a) It starts at V=0 when t=0 and rises exponentially toward V0 with the same time constant as the current.
b) It starts at V=V0 when t=0 and decreases exponentially toward zero with the same time constant as the current.
c) It starts at V=V0 when t=0 and decreases exponentially toward zero with a time constant equal to 2RC.},{
d) It starts at V=V0 when t=0 and decreases linearly to zero exactly at t=2RC.