Evaluate the limit$.$

$\backslash$lim$\_(($x$,$y$)->(3,6))(\backslash$sqrt$($x$+$y$)-3)/($x$+$y$-9)$

Select the correct choice below and, if necessary, fill in the answer box to complete your choice.

A$.\backslash$lim$\_(($x$,$y$)->(3,6))(\backslash$sqrt$($x$+$y$)-3)/($x$+$y$-9)=?($Simplify your answer.$)$

B$.$ The limit does not exist.