The sum of coefficient of integral powers of x in the binomial expansion of $(1-2 \sqrt x)^{50}$ is :

Question

$\begin{array}{1 1} \frac{1}{2} (3^{50}) \\ \frac{1}{2} (3^{50}-1) \\ \frac{1}{2} (2^{50}+1) \\ \frac{1}{2} (3^{50}+1) \end{array} $