Ans: C
Note that the projection of $EB$ on the plane $ABCD$ is $DB$. Therefore, the angle between $BE$ and the plane $ABCD$ is the angle between $DB$ and $EB$, i.e. $\angle DBE$.
Note that the projection of $EB$ on the plane $ABCD$ is $DB$. Therefore, the angle between $BE$ and the plane $ABCD$ is the angle between $DB$ and $EB$, i.e. $\angle DBE$.
