If $g(x) =\large\frac{f(x) +f(-x)}{2}$ defined over $[-3,3]$ and $f(x)=2x^2-4x+1$ then $\int \limits_{-3}^3=?$

Question

$$\begin {array} {1 1} (a)\;0 \\ (b)\;42 \\ (c)\;24 \\ (d)\;36 \end {array}$$