In the following array, what is the value of fees.length $?$

double$[][]$ fees $=\{\{3\mathrm{.}00,3\mathrm{.}50,4\mathrm{.}00,5\mathrm{.}00\},$

$\{6\mathrm{.}35,7\mathrm{.}35,8\mathrm{.}35,9\mathrm{.}00\}\}$;

$2$

$4$

$8$

none of the above