If the work done in stretching a wire by 1 mm is 2 J, the work necessary for stretching another wire of same material but with double radius of cross-section and the half the length by 1 mm (joule) is:

Question

$$(a)\; 16 \qquad (b)\; 8 \qquad (c)\;4 \qquad (d)\;\frac{1}{4}$$