Which of the following statements is accurate?

Explanation

Option A defines Mcg as the square root of M squared plus r squared, with the symbols carrying their standard meanings. Option B states that Tcp is the square root of m squared plus T squared, again with typical symbol interpretations. Option C explains that equivalent torque is the torque which, by itself, causes maximum shear stress equal to that from combined bending and torsion. Therefore, all these statements are accurate, making option D the correct choice.