Technician a Says That a PTO Driveshaft Should Be Made

Technician A says that a PTO driveshaft should be made of a solid steel bar when the auxiliary it drives has to be driven at a speed greater than 1200 rpm.Technician B says that solid PTO driveshafts can be made from round section,square section,and hex section steel stock.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B