Why should the remains be donated for three years?

It doesn't take three years to get the ashes, but it will take some time to achieve it. Under normal circumstances, medical schools or hospitals will keep the remains of donors after completing the tasks of anatomy and teaching. If there is no infectious disease or tumor attack, the medical school or hospital will complete the donation task for the donor within three years. This may be the reason why the old man thinks it will take three years to donate his body.