The polar moment of inertia of a hollow shaft of outer diameter (D) and inner diameter (d) is

• A. <img src="/_files/images/mechanical-engineering/strength-of-materials/109-278-1.png">
• B. <img src="/_files/images/mechanical-engineering/strength-of-materials/109-278-2.png">
• C. <img src="/_files/images/mechanical-engineering/strength-of-materials/109-278-3.png">
• D. <img src="/_files/images/mechanical-engineering/strength-of-materials/109-278-4.png">