The word 'formal' in formal languages means:

Which of the following definitions generates the same language as $\mathrm{L}$, where

$\mathrm{L}=\left({\mathrm{x}}^{\mathrm{n}}{\mathrm{y}}^{\mathrm{n}},\mathrm{n}\ge 1\right)?$

$\mathrm{I} .\mathrm{E}\to \mathrm{xEy} | \mathrm{xy}$

$\mathrm{II}. \mathrm{x} \mathrm{y} | + \mathrm{x}{ }^{+}\mathrm{y} {\mathrm{y}}^{+}$

${\mathrm{x}}^{+}{\mathrm{y}}^{+}$

Choose the correct statements:

The set $\left\{{\mathrm{a}}^{\mathrm{n}}{\mathrm{b}}^{\mathrm{n} }\right| \mathrm{n}=1,2,3,\dots !\}$ can be generated by the CFG: