Of 2872 persons who had received radiation treatment in childhood because of an enlarged thymus, cancer of the thyroid developed in 24, and a benign thyroid tumor developed in 52. A comparison group consisted of 5055 children who had received no such treatment none of the comparison group developed thyroid cancer but benign thyroid tumors developed in six children.
The relative risk (risk Ratio) for the benign thyroid tumor is?
Group of answer choices
15.3
0.52
15.5
2.5