Find the Directional Derivative of the Function $f ( x , y ) = ( x + 5 ) e ^ { y }$

Multiple Choice

Find the directional derivative of the function $f ( x , y ) = ( x + 5 ) e ^ { y }$ at the point $P ( 6,0 )$ in the direction of the unit vector that makes the angle $\theta = \frac { \pi } { 2 }$ with the positive x-axis.

A) $e ^ { 6 }$
B) 1
C) $5 e ^ { 6 }$
D) 11