This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli), Subject name: Microbiology
Selective agent for Mycobacteria in LJ medium is : 
Select and explain. 
A. Methylene blue, B. Malachite green, C. Mineral salt solution, D. Glycerol
B: Malachite green
Answer: B: Malachite green 
Explanation: LJ medium contains- ? Potassium dihydrogen phosphate anhydrous , Magnesium sulphate anhydrous, Magnesium citrate ? Asparagine and Glycerol ? Malachite green, 2% solution ? Eggs