What can be said about a regular language $L$ over $\{ a \}$ whose minimal finite state automaton has two states?
- $L$ must be $\{a^n \mid n \ \text{ is odd}\}$
- $L$ must be $\{a^n \mid n \ \text{ is even}\}$
- $L$ must be $\{a^n \mid n \geq 0\}$
- Either $L$ must be $\{a^n \mid n \text{ is odd}\}$, or $L$ must be $\{a^n \mid n \text{ is even}\}$
