If M, I, R, E, F, and Y are the bending moment, moment of inertia, radius of curvature, modulus of elasticity stress and the depth of the neutral axis at section, then

• A. <img src="/_files/images/civil-engineering/theory-of-structures/85-21-53-1.png">
• B. <img src="/_files/images/civil-engineering/theory-of-structures/85-21-53-2.png">
• C. <img src="/_files/images/civil-engineering/theory-of-structures/85-21-53-3.png">
• D. <img src="/_files/images/civil-engineering/theory-of-structures/85-21-53-4.png">