Choose the correct alternatives (More than one may be correct).
The total external path length, EPL, of a binary tree with $n$ external nodes is, $EPL= \sum_{w} Iw$, where $I_{w}$ is the path length of external node $w$),
- $\leq n^{2}$ always.
- $\geq n \log_{2} n$ always.
- Equal to $n^{2}$ always.
- $O(n)$ for some special trees.