An electron beam accelerated through 400 V is incident on a metallic foil. The distance between the arrays of atoms of the metal is 1.2 $\stackrel{0}{\mathrm{A}}$. What is the angular width of central maximum?

• A

  ${60}^0$

• B

  ${30}^0$

• C

  $2{\sin }^{-1}\left(\frac{2}{3}\right)$

• D

  ${37}^{\mathrm{o}}$