$\sum_{r=1}^{p} r^{3}=$ কত?

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

$\frac{p^{2}(p+1)^{2}}{4}$

$\frac{n(n+1)}{2}$

$\frac{p(p+1)}{6}$