3. Given two propositions:
(I ) The dihedral angles formed by adjacent lateral faces of the pyramid $V-A B C D$ are all equal;
(II ) The angles formed by adjacent lateral edges of the pyramid $V-A B C D$ are all equal.
For the above two propositions ().
(A)( I ) is a sufficient but not necessary condition for ( II )
(B) (I ) is a necessary but not sufficient condition for ( II )
(C)( I ) is a sufficient and necessary condition for (II )
(D)( I ) is neither a sufficient condition nor a necessary condition for (II)
3. (D).

Construct two counterexamples: As shown in Figure 2, the quadrilateral pyramid $P-ABCD$ has a rectangular base $ABCD$ (not a square), which satisfies (I) but not (II); As shown in Figure 3, the quadrilateral pyramid $P-ABCD$ has a rhombic base $ABCD$ (not a square), which satisfies (II) but not (I).