Final answer:
The storage site for fat in the central cavities (medullary) of long bones is the yellow marrow.
Step-by-step explanation:
Bone marrow, which fills the interior of most bones, consists of two types: yellow marrow and red marrow. Yellow marrow contains adipose tissue and serves as a storage site for fat. On the other hand, red marrow is responsible for hematopoiesis—the production of blood cells.
For example, the head of the femur contains both yellow and red marrow. Yellow marrow stores fat, while red marrow is responsible for blood cell production.