For the diffraction from a crystal with $\lambda = 1 Å$ and Bragg's angle $\theta = 60^{\circ}$, then for the second order diffraction $'d'$ will be

Question

$\begin{array}{1 1} (1)\; 1.15 Å \\ (2)\; 0.75Å \\ (3)\; 0.55 Å \\ (4)\; 2.1 Å \end{array}$