2. In the triangular pyramid $S$ $A B C$, $S A \perp$ plane $A B C, A B \perp A C, S A=$ $A B, S B=$ i.,$E$ is the midpoint of $S C$, $D \perp \perp S C$ intersects $A C$ at $D$. Then the degree of the dihedral angle $E-D B-C$ is ( ).
(A) $30^{\circ}$
(B) $45^{\circ}$
(C) $60^{\circ}$
(D) $75^{\circ}$
2. (C).

Let $S A=A B=1$, then $S B=B C=\sqrt{2}$.
Since $S B \perp B C, S C=\sqrt{2} \cdot \sqrt{2}=2, \angle S C A=30^{\circ}$, $\angle E D C=60^{\circ}$, it is easy to prove that $\angle E D C$ is the dihedral angle of $E-D B-C$.