Two point masses having mass $m$ and $2m$ are placed at a distance $d$. The point on the line joining the point masses,where the gravitational field intensity is zero,will be at a distance ............

• A
  $\frac{2d}{\sqrt{3}+1}$ from point mass $2m$
• B
  $\frac{2d}{\sqrt{3}-1}$ from point mass $2m$
• C
  $\frac{d}{1+\sqrt{2}}$ from point mass $m$
• D
  $\frac{d}{1-\sqrt{2}}$ from point mass $m$