Final answer:
Chelsea is engaged in the maintenance phase of the SDLC by updating software, and ensuring it meets continuing and changing user needs.
Step-by-step explanation:
Chelsea is involved in the maintenance phase of the Software Development Life Cycle (SDLC). The SDLC consists of several distinct stages: requirements gathering and analysis, design, implementation or coding, testing, deployment, and maintenance. The maintenance phase is where updates and improvements are made after the software has been deployed to ensure that it continues to meet user needs and remains compatible with changing systems and technologies. Chelsea's role in making updates indicates that she is actively ensuring that the software continues to function correctly and is adapting to new requirements or fixing issues that have emerged.