Read this and answer the question. If the question is unanswerable, say "unanswerable".

Charleston is the primary medical center for the eastern portion of the state. The city has several major hospitals located in the downtown area: Medical University of South Carolina Medical Center (MUSC), Ralph H. Johnson VA Medical Center, and Roper Hospital. MUSC is the state's first school of medicine, the largest medical university in the state, and the sixth-oldest continually operating school of medicine in the United States. The downtown medical district is experiencing rapid growth of biotechnology and medical research industries coupled with substantial expansions of all the major hospitals. Additionally, more expansions are planned or underway at another major hospital located in the West Ashley portion of the city: Bon Secours-St Francis Xavier Hospital. The Trident Regional Medical Center located in the City of North Charleston and East Cooper Regional Medical Center located in Mount Pleasant also serve the needs of residents of the city of Charleston.

What medical district is experiencing growth in biotechnology and medical research field?
The downtown medical district