Final answer:
Prescribing exercise for a cancer patient/survivor can be challenging due to various reasons, including the stage/progression of the person's cancer.
Step-by-step explanation:
Prescribing exercise for a cancer patient/survivor can be challenging due to various reasons. While all the options mentioned in the question can be valid challenges, option b. The stage/progression of the person's cancer, can be particularly challenging. The stage of cancer indicates the severity and spread of the cancer, and it plays a significant role in determining the appropriate exercise program for a cancer patient.