If Rolle's theorem holds for the function $f(x) = 2{x^3} + b{x^2} + cx,\,x\, \in \,\left[ { - 1,1} \right]$ at the point $x = \frac{1}{2}$ , then $(2b+c)$ is equal to 

  • A

    $1$

  • B

    $-1$

  • C

    $2$

  • D

    $-3$

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