Answer:
B. sudden muscle weakness
Explanation:
 Myasthenia gravis is an autoimmune disease in which communication between the nerves and muscles is affected, producing episodes of muscle weakness.
  The cholinergic properties of neostigmine are based on its inhibitory effect on  cholinesterase, which stabilizes acetylcholine, whose action is  enhanced and prolonged. At the system level  digestive and genitourinary, as well as other smooth muscle organs, neostigmine  causes contractions and increased peristalsis. Neostigmine  neutralizes blockage  neuromuscular disorders induced by curare myorelaxants and preparations of the same type (i.e., non-depolarizing) but  synergistically interacts with depolarizing myorelaxants.
 As with other cholinergics, overdosage with neostigmine may cause  cholinergic crisis characterized by marked muscle weakness (or increase of this symptom in myasthenics). If the condition is not identified, there is a risk of death due to respiratory muscle paralysis. Bradycardia, or  paradoxically, tachycardia may also occur.