When a bar of length l and diameter d is rigidly fixed at the upper end and hanging freely, then the total elongation produced in the bar due to its own weight is (where w = Weight per unit volume of the bar)

• A. <img src="/_files/images/mechanical-engineering/strength-of-materials/84-21-1.png">
• B. <img src="/_files/images/mechanical-engineering/strength-of-materials/84-21-2.png">
• C. <img src="/_files/images/mechanical-engineering/strength-of-materials/84-21-3.png">
• D. <img src="/_files/images/mechanical-engineering/strength-of-materials/84-21-4.png">