Find the middle term in the expansion of $(3-\large\frac{x^3}{6})^7$

Question

$\begin{array}{1 1}(A)\;\large\frac{35}{48}\\(B)\;\large\frac{48}{35}\\(C)\;\large\frac{35}{48}\normalsize x^{12}\\(D)\;\large\frac{35}{48}\normalsize x^{10}\end{array} $