Find the Sum or Difference $( p + 3 q ) ( p - 3 q )$

Multiple Choice

Find the sum or difference.
- $( p + 3 q ) ( p - 3 q )$

A) $p ^ { 2 } - 6 q ^ { 2 }$
B) $p ^ { 2 } - 6 p q - 9 q ^ { 2 }$
C) $p ^ { 2 } - 9 q ^ { 2 }$
D) $p ^ { 2 } + 6 p q - 9 q ^ { 2 }$