If $\alpha$ and $\beta$ are distinct complex numbers with $\mid \beta\mid=1$,then value of $\big|\large\frac{\beta-\alpha}{1-\overline{\alpha}\beta}\big|$ equals

Question

$\begin{array}{1 1}(A)\;1&(B)\;2\\(C)\;\mid \alpha\mid&(D)\;\text{None of these}\end{array} $