This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuromuscular Blocker, Subject name: Anaesthesia
A lady after undergoing surgery under general anaesthesia with no intra surgical complication complained of respiratory difficulty. Po2 low. Not able to lift her head and leg. what can be the cause 
Select and explain. 
A. Prolonger action of muscle relaxant, B. Respiratory acidosis, C. Pulmonary embolism, D. Fentanyl chest rigidity
A: Prolonger action of muscle relaxant
Answer: A: Prolonger action of muscle relaxant 
Explanation: This is a case of inadequate reversal from neuromuscular blocker. Residual paralysis Can occur after general Anaesthesia C/F - Patient conscious , unable to breathe adequate tidal volume , motor weakness, desaturation M/n- suppo the ventilation