The shortest distance between the lines \( \frac{x-3}{2}=\frac{y+15}{-7}=\frac{z-9}{5} \) and \( \frac{x+1}{2}=\frac{y-1}{1}=\frac{z-9}{-3} \) is:
\( 4\sqrt{3} \)
\( 5\sqrt{3} \)
\( 6\sqrt{3} \)
\( 8\sqrt{3} \)