This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mycobacterial Diseases (TB, Leprosy and MAC), Subject name: Pharmacology
Which of the following anti-tubercular drug is least hepatotoxic? 
Select and explain. 
A. Rifampicin, B. Pyrazinamide, C. Ethambutol, D. INH
C: Ethambutol
Answer: C: Ethambutol 
Explanation: Ethambutol among the given options is the least hepatotoxic antitubercular drug. Ethambutol side-effect includes Dose dependent adverse effect Red green colour blindness (optic neuritis) which is initially reversible but later becomes irreversible. Therefore it is avoided in children < 6yr.