Two wires A and B of same length and of the same material have the respective radii \[{{r}_{1}}\] and \[{{r}_{2}}\]. Their one end is fixed with a rigid support, and at the other end equal twisting couple is applied. Then the ratio of the angle of twist at the end of A and the angle of twist at the end of B will be [AIIMS 1980]

• A.                 \[\frac{r_{1}^{2}}{r_{2}^{2}}\]   
• B.                 \[\frac{r_{2}^{2}}{r_{1}^{2}}\]
• C.                 \[\frac{r_{2}^{4}}{r_{1}^{4}}\]   
• D.                 \[\frac{r_{1}^{4}}{r_{2}^{4}}\]