Find the Slope of the Line Tangent to the Graph $\left( \frac { \pi } { 2 } - x \right)$

Multiple Choice

Find the slope of the line tangent to the graph of y = sin $\left( \frac { \pi } { 2 } - x \right)$ - cos x at x =
$\frac { \pi } { 4 }$ .

A) $\frac { 1 } { 2 }$
B) 0
C) $\frac { \sqrt { 2 } } { 2 }$
D) $\sqrt { 2 }$