If the letters of the word ALGORITHM are arranged at random in a row what is the probability the letters GOR must remain together as a unit ?

Question

$\begin{array}{1 1}(A)\;\large\frac{1}{62}\\(B)\;\large\frac{1}{72}\\(C)\;\large\frac{1}{52}\\(D)\;\text{None of these}\end{array} $