In the circuit shown below, the internal resistance of the battery is 1.5 O and its e.m.f. is 20 V. A multimeter in its voltage mode is connected between P and Q. Internal resistance of the multimeter can be taken to be infinite. The multimeter reading is
(a) -2.5 V
(b) -4 V
(c) 4 V
(d) 2.5 V
