Step 1: Recall geometric property.
A regular hexagon can appear as a cross-section of a cube (under a diagonal cut) or a regular hexagonal prism.
Step 2: Analyze shapes.
- (A): Square prism → can give square or rectangle, not a hexagon.
- (B): Cuboid → only rectangles/squares.
- (C): Irregular extrusion → cannot yield a regular hexagon.
- (D): Hexagonal prism → cross-section by a plane parallel to base gives a perfect hexagon. With a proper diagonal cut, it yields a regular hexagon.
Step 3: Conclude.
Thus, only option (D) gives a regular hexagonal cross-section.
Final Answer:
\[
\boxed{\text{D}}
\]