A parallel beam of electrons travelling in $x$-direction falls on a slit of width $d$ (see figure). If after passing the slit, an electron acquires momentum $p_{_y}$ in the $y$-direction then for a majority of electrons passing through the slit ($h$ is Planck's constant) : <br>

Question

( A ) $|p_{_y}| d \simeq h$
( B ) $|p_{_y}| d < h$
( C ) $|p_{_y}| d >> h$
( D ) $|p_{_y}| d > h$