18.A R-L circuit has a 60 V battery, a 45 H inductor, a 25 Ω resistor, and a switch S in series. Initially, S is open and there is no magnetic flux in the inductor. At t = 0 s, S is closed. When the current is 1.5 A, the rate of change of the current is closest to (A/s) (A) 0.67 (B) 0.58 (C) 0.50 (D) 0.75 (E) 0.83