The length of the sub tangent at (2,2) to the curve $x^5 =2y^4$ is :

Question

\[\begin {array} {1 1} (1)\;\frac{5}{2} & \quad (2)\;\frac{8}{5} \\ (3)\;\frac{2}{5} & \quad (4)\;\frac{5}{8} \end {array}\]