A 16 MeV beam has the following beam characteristics: D-max is 3.1 cm, 90% depth is 5.2 cm , 80% depth is 5.7 cm, surface is covered by 93%. The doctor wants to prescribe to the 90% isodose line. The doctor wants your input on how much bolus they should use. The doctor wants to make sure skin gets at least 100% coverage. How much bolus do you tell the doctor that they need to use? A. No bolus needed B. 0.5 C. 1.5