A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
(a) A P-type semiconductor (b) An N-type semiconductor
(c) A PN-junction (d) An intrinsic semiconductor
(c) When polarity of the battery is reversed, the P-N junction becomes reverse biased so no current flows.