Final answer:
The stage in which you build prototypes to test navigation is called the Prototype stage.
Step-by-step explanation:
The stage in which you build prototypes to test navigation is called the Prototype stage. Prototypes are trial working models of a design that are built to test design decisions and identify potential problems. The purpose of prototyping is to provide additional understanding of the design and its performance, and to test whether the design will work as expected. Prototypes are tested and evaluated to see whether the design meets all constraints and performs acceptably relative to the criteria.