What is the root$-$mean$-$square $($a$.$k$.$a$.$ "effective$)"$ current value for an AC current with an amplitude $($a$.$k$.$a$.$ peak$)$ value of $15\mathrm{.}4$ A $?$

$($A$)15\mathrm{.}4$ A

$($B$)7\mathrm{.}70$ A

$($C$)10\mathrm{.}9$ A

$($D$)3\mathrm{.}92$ A

$($E$)2\mathrm{.}77$ A