Two shafts will have equal strength, if

Answer: Option D

Two shafts will have equal strength if the twisting moment of both the shafts is the same.

Twisting moment determines the ability of a shaft to resist the applied torque without failure. It is given by the formula:

T = τ × Z_p

Where:

T = Twisting moment

τ = Shear stress

Z_p = Polar section modulus

Equal twisting moments imply that the shafts will experience the same level of stress and deformation under the applied torque, ensuring they have equal strength.

Therefore, Option D is the correct answer.