(c)
$\lim_{n \rightarrow \infty}\frac{1^{2} + 2^{2} + 3^{2} + \ldots + n^{2}}{n^{3}}$
$= \lim_{n \rightarrow \infty}\frac{\sum_{}^{}n^{2}}{n^{3}}$
$= \lim_{n \rightarrow \infty}\frac{n(n + 1)(2n + 1)}{6n^{3}}$
$= \lim_{n \rightarrow \infty}\frac{1}{6}\left( 1 + \frac{1}{n} \right)\left( 2 + \frac{1}{n} \right)\$
$= \frac{1}{3}$