Answer: People who have received radiation treatment are 15 times more likely to develop benign thyroid tumors relative to does who have not.
Explanation:
Relative risk of benign thyroid tumor = (52/2872)/(6/5055)
= 0.018/0.0012
= 15
The is should be C, Im not 100% sure though...
The correct answer is D, white blood cells.
We know that red blood cells deliver nutrients and are not apart of the immune system; platelets are responsible for coagulation, which has nothing to do with the immune system, and plasma is a substance that, again, has nothing to do with immunity. White blood cells are the only things that fight disease (antibodies are white blood cells)!
I hope I helped!
(By nothing I meant very little to none).