Final answer:
Application program modules are specified during the Design phase of the SDLC, where the detailed design is established and readied for implementation.
Step-by-step explanation:
The phase of the Systems Development Life Cycle (SDLC) where application program modules are specified is the Design phase. During this phase, the selected design is developed into more detail. The team establishes the design architecture, identifies physical and functional chunks, and determines shapes, dimensions, materials, and fabrication processes. Moreover, product components are identified, leading to the creation of prototypes and models that can be iteratively tested and refined as needed.
In the Design phase, after the initial research and analysis, the various details, ideas, and constraints come together to refine the design, which includes putting pencil to paper or cursor to screen, in preparation for implementation. This phase requires a collaborative effort to ensure that all aspects of the application are accounted for and can be successfully translated into actual code during the subsequent Implementation phase.