JEE Main 1997 Chemistry question on Atomic Structure

1. A.
   $\sqrt{6}\left(\dfrac{h}{2\pi}\right)$
2. B.
   $\sqrt{2}\left(\dfrac{h}{2\pi}\right)$
3. C.
   $\left(\dfrac{h}{2\pi}\right)$
4. D.
   $2\left(\dfrac{h}{2\pi}\right)$

[1997]