This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following is an inducer of microsomal enzymes: 
Select and explain. 
A. Phenobarbitone, B. Paracetamol, C. Digoxin, D. Penicillin
A: Phenobarbitone
Answer: A: Phenobarbitone 
Explanation: None