Find the Directional Derivative to the Given Function at the Specified

Multiple Choice

Find the directional derivative to the given function at the specified point $P$ in the direction of the vector $\vec { u }$ $f ( x , y ) = x ^ { 3 } - x ^ { 2 } y , P = ( 1,2 ) , \vec { u } = \langle \sqrt { 3 } , 1 \rangle$

A) $\frac { \sqrt { 3 } + 1 } { 2 }$
B) $2 \sqrt { 3 } - 4$
C) $\frac { - \sqrt { 3 } - 1 } { 2 }$
D) $- 1$