The Slope of the Tangent Line to the Curve $y \cos x + e ^ { y } = 4$

Multiple Choice

The slope of the tangent line to the curve $y \cos x + e ^ { y } = 4$ at $\left( \frac { \pi } { 2 } , \ln 4 \right)$ is

A) 0
B) 4
C) $\frac { \ln 4 } { 4 }$
D) $\frac { 4 + \ln 4 } { 4 }$
E) None of the above