The Systems Development Life Cycle (SDLC) is the process of creating or altering the systems; and the models and methodologies that people use to develop these systems. Which of the following are the

While testing is a critical activity performed throughout multiple phases of the SDLC (e.g., unit testing during development, system testing during implementation), it is typically an activity integrated within phases rather than a standalone, distinct phase at the same level as the others in common SDLC models like NIST SP 800-64.

Implementation is a standard SDLC phase where the system is installed, configured, and made operational for its intended users.

Operation/maintenance is a crucial SDLC phase focused on the ongoing running, monitoring, support, and necessary updates of the system after deployment.

Development/acquisition represents the phase where the system is either built from scratch, customized, or procured as an off-the-shelf solution according to design specifications.

Disposal is the final SDLC phase where the system and its associated data are securely retired, de-provisioned, and properly disposed of.

Initiation is the initial SDLC phase where the need for a new system is identified, its feasibility is assessed, and preliminary requirements are established.