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
True about the orphan drug is: 
Select and explain. 
A. Developed for orphans, B. Drugs used very rarely, C. Drugs used for rare diseases, D. Rare drug for common diseases
C: Drugs used for rare diseases
Answer: C: Drugs used for rare diseases 
Explanation: Orphan Drugs are drugs or biological products for diagnosis/treatment/prevention of a rare disease or condition, or a more common disease (endemic only in resource-poor countries) for which there is no reasonable expectation that the cost of developing and marketing it will be recovered from the sales of that drug.
The list includes sodium nitrite, fomepizole, liposomal amphotericin B, ancrod, rifabutin, succimer, somatropin, digoxin immune Fab (digoxin antibody), liothyronine (T3) and many more.