If the length of the sides of a triangle are decided by the three throws of a single fair die, then the probability that the triangle is of maximum are given that it is an isosceles triangle , is :

Question

$\begin{array}{1 1} \frac{1}{26} \\ \frac{1}{27} \\ \frac{1}{21}\\ \frac{1}{15} \end{array} $