Let $y = \sqrt { x }$ Then the Curvature K at (4, 2) Is

Multiple Choice

Let $y = \sqrt { x }$ . Then the curvature K at (4, 2) is

A) $\frac { 2 } { 25 \sqrt { 5 } }$
B) $\frac { \sqrt { 2 } } { 11 }$
C) $\frac { 2 } { 5 \sqrt { 5 } }$
D) $\frac { 2 } { 17 \sqrt { 17 } }$
E) $\frac { 1 } { 2 }$