Man develops wrist drop after sustaining a complete fracture of the upper arm *** with extensive tissue damage. Fracture was reduced successfully and ends of vessels and damaged nerves were apposed and surgically rejoined. Despite physical therapy, the extensor muscles have a decre volume and can contract only weakly. Wound healing and flexion are good. Most likely cause of this condition is abnormal function of which following?
a.neurotrophic input
b.tendon stretch receptors
d.glucose transporters