Does the Union command work only on 2D objects, or can it operate on 3D solids as well when combining volumes to form a single body?

Introduction / Context:
Union is a Boolean operation used across 2D (regions) and 3D (solids) contexts. The claim that Union works only on 2D objects is wrong; it is widely used to merge 3D solids into a single solid, a key step in constructive solid geometry (CSG).

Given Data / Assumptions:

• We are modeling with true 3D solids, not just wireframes.
• Overlapping volumes are selected for combination.
• CAD supports standard Booleans: Union, Subtract, Intersect.

Concept / Approach:
Union adds volumes together wherever solids overlap/touch, yielding one continuous manifold solid suitable for subsequent operations like fillet, shell, or subtract.

Step-by-Step Solution:

Verification / Alternative check:
Section or slice the result to see internal continuity; mass properties validate combined volume and centroid shift.

Why Other Options Are Wrong:
“Correct” contradicts real 3D behavior. “Union is 2D-only,” “requires perspective,” and “is mesh-only” are false; meshes and solids are distinct, and perspective is a display mode, not a Boolean requirement.

Common Pitfalls:
Trying to Union non-overlapping bodies; mixing incompatible object types (e.g., surfaces vs solids) without proper conversion.

Final Answer:
Incorrect