A segment $AB$ of 2 m length is divided internally by $C$ into two parts such that $AC^2=AB\times AC$.The length of the part $CB$ is _____

Question

$\begin{array}{1 1}(A) \;(3+\sqrt 5)\;m\\(B)\;(3-\sqrt 5)\;m \\(C)\;(5-\sqrt 3)\;m \\(D)\;(5+\sqrt 3)\;m \end{array}$