Consider the following languages:
- $L1=\left\{ww \mid w \in \{a,b\}^*\right\}$
- $L2=\left\{ww^R \mid w \in \{a,b\}^*, w^R \text{ is the reverse of w} \right\}$
- $L3=\left\{0^{2i} \mid \text{ i is an integer} \right\}$
- $L4= \left\{ 0^{i^2} \mid \text{ i is an integer} \right\}$
Which of the languages are regular?
- Only $L1$ and $L2$
- Only $L2, L3$ and $L4$
- Only $L3$ and $L4$
- Only $L3$