Answer:
Leukemia occurs in the bone marrow.
Step-by-step explanation:
A bone marrow transplant is needed to treat her leukemia because leukemia occurs in the bone marrow. Leukemia is a type of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells which only be treated when the infected bone marrow is replaced with healthy bone marrow. Doctors used cord blood as the source of blood stem cells for bone marrow transplant because cord blood has stem cells which has the ability to treat leukemia.