The figure shows a portions of the graph $y=2 x-4 x^{3}$. The line $\mathrm{y}=\mathrm{c}$ is such that the areas of the regions marked I and II are equal. If $a, b$ are the $x$-coordinates of $A, B$ respectively, then $\mathrm{a}+\mathrm{b}$ equals

• Correct answer
  A

  $\frac{2}{\sqrt{7}}$
• B

  $\frac{3}{\sqrt{7}}$
• C

  $\frac{4}{\sqrt{7}}$
• D

  $\frac{5}{\sqrt{7}}$

Hence, the correct answer is option: 'A'.