$12.$ What is the big O function of the following growth rate function $g(n)?$

$h(n)=100nlogn+3n+9$

$f(n)=5n^2-4n+100logn$

$g(n)=h(n)+f(n)$

O$($nlogn$)$

$O(n)$

O$($logn$)$

$O(n^2)$