Find the Directional Derivative of the Function $f ( x , y ) = x ^ { 2 } + y ^ { 2 }$

Multiple Choice

Find the directional derivative of the function $f ( x , y ) = x ^ { 2 } + y ^ { 2 }$ at the point $( 1,2 )$ in the direction $\theta = \frac { \pi } { 2 }$ .

A) 0
B) 1
C) 2
D) 3
E) 4
F) 5
G) 6
H) 7