If Rolle’s theorem holds for the function $f (x)=2x^3+bx^2+cx, x \in [-1, 1],$ at the point $x= \large\frac{1}{2}$, then $2b+c$ equals :

Question

$\begin{array}{1 1} 1 \\-1 \\ 2 \\ -3 \end{array} $