This is a question about notation. If you were given such a question, you clearly are expected to know what things such as "$\displaystyle 0\le x\le 1$" and "$\displaystyle \x\in \{0, 1\}$" mean. Do you not know that? The notations should be given in your book.
The fact that "x is a natural number" is crucial here. Once you have found out what the various notations mean, write down the values of all natural numbers that satisfy each.