<prompt> The resting memebrane potential of smooth muscle is:70 - 80 mV80 - 90 mV90- 100 mV110-120 mV  <response>: 70 - 80 mV: Ref: 55, 68, 78-G, 154 - 803-SL 84- Ganong 23rd The resting membrane potential of skeletal muscle cardiac muscle, NMJ is about - 90 mV The resting membrane potential in neurons a bout - 70 mV The resting membrane potential in other sensory receptor cells is usually 70-90 mV however in the visual receptor the RMP is about - 40 mVThe RMP in visceral smooth muscle ranges - 50 and 75 mV, sometimes it reaches the low level of - 25. The pecularity of the RMP is that very much unstable 154-SL The option A is probably correct regarding range - 50 - 75 mV 