Final Answer:
The last resort treatment for aplastic anemia is 1) Bone marrow transplant.
Step-by-step explanation:
Aplastic anemia is a condition characterized by a decrease in the number of blood cells. When other treatments like immunosuppressive therapy or medications fail, a bone marrow transplant becomes a last resort. In this procedure, damaged or diseased bone marrow is replaced with healthy marrow from a donor, typically a matching sibling or unrelated donor. The transplant aims to restore the production of blood cells. While effective, a bone marrow transplant involves significant risks and complications, making it a reserved option when other treatments are unsuccessful or inappropriate.
Option 1 is the answer.