Add or Subtract as Indicated $-9 n+9$ $\underline{-12 n-3}$ A) $-21 n+6$

Add or subtract as indicated.
-Add.
$-9 n+9$
$\underline{-12 n-3}$

A) $-21 n+6$
B) $-3 n+12$
C) $3 n+12$
D) $21 n+6$