In the original concept for a general-purpose CAD system architecture, what should the system provide to support users and applications effectively?

Introduction / Context:
Computer-Aided Design (CAD) platforms are more than drawing tools; they are extensible environments. A solid CAD architecture must orchestrate user interaction, host application modules (e.g., parametric modeling, simulation), and supply core utilities that standardize geometry, graphics, file I/O, and constraints.

Given Data / Assumptions:

• Users interact through devices (mouse, tablet, touch) and commands.
• Applications extend capabilities: drafting, solids, surfaces, simulation.
• Core services include geometry kernels, graphics pipelines, and resource managers.

Concept / Approach:
An effective CAD system is a layered stack: at the bottom, system utilities; above, an application framework; at the top, an interaction layer that translates user actions into model edits. Therefore, all three elements in options A–C are essential and collectively define the platform’s capability envelope.

Step-by-Step Solution:

Verification / Alternative check:
Vendor and academic references describe CAD as an environment exposing APIs, services, and interactive tools, which aligns with selecting “All of the above.”

Why Other Options Are Wrong:

Common Pitfalls:
Thinking of CAD as a monolithic app; sustainable CAD ecosystems rely on modular services and app frameworks.

Final Answer:
All of the above