This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Treatment for achalasia associated with high rate of recurrence 
Select and explain. 
A. Pneumatic dilatation, B. Laparoscopic myotomy, C. Open surgical myotomy, D. Botulinum toxin injection
D: Botulinum toxin injection
Answer: D: Botulinum toxin injection 
Explanation: Treatment of choice in case of high chance of recurrence is Endoscopic injection of botulinum toxin to sphincter. Botulinum toxin is neurotoxic protein derived from Clostridium botulinum is highly toxic poisonous substance. Very small amount is used for therapeutic purpose. 7 types of toxins are found. It blocks cholinergic nerve ends reducing the cholinergic acetylcholine release causing flaccid paralysis of muscles. Reference: SRB's Manual of Surgery, 6th Edition, page no= 791.