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: Dental
All the following drugs are effective in t/t of ptyriasis versicolor except – 
Select and explain. 
A. Selenium sulphide, B. Ketoconazole, C. Grieseofulvin, D. Clotrimazole
C: Grieseofulvin
Answer: C: Grieseofulvin 
Explanation: Griseofulvin is effective only against dermatophytes. It is ineffective against T. versicolor and candida.