If x is a solution of the equation, $\sqrt{2x + 1} - \sqrt{2x - 1} = 1, \begin{pmatrix} x \geq \frac{1}{2} \end{pmatrix}$, then $\sqrt{4x^2-1}$ is equal to :

Question

$\begin{array}{1 1}(1)\; \frac{3}{4} \\ (2)\; \frac{1}{2} \\ (3)\; 2 \\ (4)\; 2\sqrt{2} \end{array}$