Use the Product-To-Sum Formulas to Rewrite the Product as a Sum

Multiple Choice

Use the product-to-sum formulas to rewrite the product as a sum or difference.​ $$4 \cos \frac { \pi } { 2 } \sin \frac { 5 \pi } { 4 }$$ ​

A) ​ $2 \left( \sin \frac { 7 \pi } { 4 } - \sin \frac { 3 \pi } { 4 } \right)$
B) ​ $2 \left( \cos \frac { 7 \pi } { 4 } - \cos \frac { 3 \pi } { 4 } \right)$
C) ​ $2 \left( \sin \frac { 7 \pi } { 4 } + \cos \frac { 3 \pi } { 4 } \right)$
D) ​ $2 \left( \sin \frac { 7 \pi } { 4 } + \sin \frac { 3 \pi } { 4 } \right)$
E) ​ $2 \left( \cos \frac { 7 \pi } { 4 } + \cos \frac { 3 \pi } { 4 } \right)$