Factor the Trinomial Completely $m ^ { 2 } - 9 m + 18$

Multiple Choice

Factor the trinomial completely. $m ^ { 2 } - 9 m + 18$

A) $( m + 3 ) ( m + 6 )$
B) $( m + 3 ) ( m - 6 )$
C) $( m - 3 ) ( m - 6 )$
D) $( m - 3 ) ( m + 6 )$
E) not factorable