Answer: b. False
Step-by-step explanation:
Using the same material and the same design specifications, a shaft designed using the Maximum Shear Stress theory will NOT use the less amount of material than a shaft designed using Distortion Energy theory.
Distortion Energy Theory affirms that materials deform when it experiences shear loading outside an hydrostatic conditioner. But Mass Shear Stess Theory suggests that shaft loading done in pure torsion yields when the value of the shear stress at maximum is greater than half the material's yield strength.
This separate theories therefore makes the above statement in the question false.