This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
True about orphan drugs: 
Select and explain. 
A. Drug used for orphans, B. They are rare drugs, C. They are emergency drugs, D. Drugs for rare diseases
D: Drugs for rare diseases
Answer: D: Drugs for rare diseases 
Explanation: Ans. (d) Drugs for rare diseases