What is the Stage$-$Gate process according to the textbook?

a formal process of data collection and analysis that is used in the product development process

the formal company process of data of structure put in place to ensure product adoption

the assessment process that occurs during the maturity stage of the Product Life Cycle

It is the formal description of how new products are commercialized through staging process.

The Stage$-$Gate process occurs, and is limited to$,$ the decline stage of the Product Life Cycle when products are harvested.