If $A(4,7,8),\:B(2,3,4),\:C(2,5,7)$ are vertices of a triangle then the length of internal bisector of angle $A$ is ?

Question

$\begin{array}{1 1}(A) \large\frac{3\sqrt {34}}{2} \\ (B) \large\frac{2\sqrt {34}}{3} \\(C) \large\frac{\sqrt {34}}{2} \\ (D) \large\frac{\sqrt {34}}{3} \end{array} $