\( \displaystyle \lim_{n\to\infty}\frac{(1^{2}-1)(n-1)+(2^{2}-2)(n-2)+\cdots+((n-1)^{2}-(n-1))\cdot 1}{(1^{3}+2^{3}+\cdots+n^{3})-(1^{2}+2^{2}+\cdots+n^{2})} \) is equal to:
\( \frac{3}{4} \)
\( \frac{1}{3} \)
\( \frac{2}{3} \)
\( \frac{1}{2} \)