The sum of coefficients of integral powers of x in the binomial expansion of

$\frac{1}{2}\left(3^{50}-1\right)$

 $\frac{1}{2}\left(2^{50}+1\right)$

$\frac{1}{2}\left(3^{50}+1\right)$

$\frac{1}{2}\left(3^{50}\right)$