Factor
- $$u ^ { 2 } - 4 u v - 21 v ^ { 2 }$$

Multiple Choice

Factor.
- $$u ^ { 2 } - 4 u v - 21 v ^ { 2 }$$

A) $( u + 3 v ) ( u - 7 v )$
B) $( u - 3 v ) ( u + v )$
C) $( u - v ) ( u + 7 v )$
D) $( u - 3 v ) ( u + 7 v )$