125.A simplified four-stage model is sufficient to discriminate between the various factors which must be managed at different stages of development. Which of the following is not normally a stage in this process?
选项：

A:Concept generation – identifying the opportunities for new products and services
B:Product development- translating the selected concepts into a physical product
C:Project assessment and selection – screening and choosing projects which satisfy certain criteria
D:Production planning - manufacturing design and prototyping