Let the set of all natural numbers be $N$. Which of the following are countable sets?
- The set of all functions from $N$ to $\{0, 1\}$
- The set of all functions from $\{0, 1\}$ to $N$
- The largest subset of $N$
- I, II, and III
- I and II only
- II and III only
- I and III only