What is a prototype in the engineering design process?

A prototype in the engineering design process is an initial model used to test and evaluate a design. Its primary function is to allow designers and engineers to explore ideas, assess functionality, and identify potential issues before moving forward to more advanced stages of development. Prototypes can vary in complexity, from simple sketches or digital simulations to more sophisticated physical models. They play a crucial role in refining the design, ensuring it meets the necessary requirements and specifications based on real-world feedback and testing.

The other options suggest concepts that do not align with the purpose of a prototype. A theoretical concept without physical form cannot be tested, and a final product ready for market implies that it has already gone through the prototype stage. Meanwhile, a detailed plan that does not require real testing contradicts the iterative nature of design, where testing is essential to validate assumptions and improve the product through practical analysis.