The piecewise function $f : R \rightarrow R$ is defined as $f ( x ) = \left\{ \begin{array} { c l } 3 x + 1 , & x \text { is rational } \\ x ^ { 2 } , & x \text { is irrational } \end{array} \right.$
Accordingly, which of the following is $( f \circ f ) \left( \frac { \sqrt { 2 } } { 2 } \right)$?\\
A) $3 \sqrt { 2 } + 2$\\
B) $\sqrt { 2 } + 2$\\
C) $\frac { 1 } { 4 }$\\
D) $\frac { 5 } { 2 }$\\
E) $\frac { 7 } { 2 }$