Give English descriptions for the following languages. [1 pt each]
(a) L=\left\{0^{n} 1^{n}: n \in \mathbb{N}\right\}
(b) M=\left\{w w^{r}: w \in \Sigma^{*}\right\}
(c) The language recursively defined as follows: \varepsilon \in O and if u, v \in O then 1 u 0 v, 0 u 1 v \in O.