Two rods A and B of the same material and length have their radii \[{{r}_{1}}\] and \[{{r}_{2}}\] respectively. When they are rigidly fixed at one end and twisted by the same couple applied at the other end, the ratio \[\left( \frac{Angle\,of\,twist\,at\,the\,end\,of\,A}{Angle\,of\,twist\,at\,the\,end\,of\,B} \right)\]

• A. \[r_{1}^{2}/r_{2}^{2}\]
• B. \[r_{1}^{3}/r_{2}^{3}\]
• C. \[r_{2}^{4}/r_{1}^{4}\]
• D. \[r_{1}^{4}/r_{2}^{4}\]