The Theory That the Immune System Actively Monitors and Eliminates

The theory that the immune system actively monitors and eliminates cancer cells is supported by the observation(s) that

A) AIDS patients have higher rates of some types of cancer than other populations.
B) transplant patients on immunosuppressive therapy have higher rates of some types of cancer than other populations.
C) patients who are deficient in adenosine deaminase and on immunosuppressive therapy have higher rates of some types of cancer than other populations.
D) both AIDS patients and transplant patients have higher rates of some types of cancer than other populations.
E) both AIDS patients and patients who are deficient in adenosine deaminase and on immunosuppressive therapy have higher rates of some types of cancer than other populations.