Find the Value of the Determinant $\left| \begin{array} { l l } a & b \\b & a\end{array} \right|$

Multiple Choice

Find the value of the determinant.
$\left| \begin{array} { l l } a & b \\b & a\end{array} \right|$

A) 2ab
B) $a ^ { 2 } + b ^ { 2 }$
C) $a ^ { 2 } - b ^ { 2 }$
D) 0