Which phase answers the questions of who will use the system, what the system…

In the Software Development Life Cycle (SDLC), each phase is defined by the specific set of questions it answers about the system being built. The Analysis phase (also called Requirements Analysis or Systems Analysis) is the stage where analysts determine WHO will use the system, WHAT functions it must perform, and WHERE and WHEN it will be used — establishing the complete set of user and functional requirements before any technical design work begins.

Applying this to the phase names in the question:

• Design describes HOW the system will be built — its architecture, interfaces, and data structures — once the requirements identified during analysis are already known.

• Implementation is the phase where the designed system is actually coded, unit-tested, and deployed into use.

• Planning comes before analysis; it establishes the project's scope, feasibility, schedule, and resource allocation, but it does not itself determine who will use the system or what the system will do.

Cross-checking against the standard SDLC ordering (Planning -> Analysis -> Design -> Implementation), the who/what/where/when questions are specifically the output of the Analysis phase, which confirms Analysis as the phase the question describes. This is also the option marked correct in the HTET 2023 Computer Science official answer key.