Final answer:
In the United States, the Orphan Drug Act of 1983 provides special incentives for the development of drugs for rare diseases, including tax credits, grant funding, and market exclusivity.
Step-by-step explanation:
The special incentives for the development of drugs for rare diseases in the United States are provided under the Orphan Drug Act of 1983. This act encourages pharmaceutical companies to develop treatments for diseases that have a small patient population, thereby not offering a significant financial incentive under ordinary market conditions. The Orphan Drug Act offers benefits like tax credits, grant funding, assistance with clinical research, and a period of market exclusivity upon the drug's approval.