Which ITIL practice focuses on maintaining efficient service quality?

The practice that focuses on maintaining efficient service quality is Service Level Management. This practice is crucial in defining, negotiating, and managing the service level agreements (SLAs) that set expectations for service delivery between the service provider and the customers. By establishing clear service level targets, Service Level Management ensures that the services are delivered in accordance with agreed-upon standards, which helps maintain consistency and quality over time.

In addition to negotiating and monitoring SLAs, this practice also involves regular reviews and assessments of service performance. This ensures that any gaps in service delivery are identified and addressed promptly, thereby sustaining the overall quality of services offered to customers. Furthermore, Service Level Management plays a significant role in continual service improvement (CSI) initiatives by analyzing service performance data and soliciting customer feedback for enhancement opportunities.

The other practices, while essential in their contexts, do not primarily focus on the ongoing maintenance of service quality. Change Control is concerned with managing changes to avoid disrupting services; Incident Management focuses on restoring service quickly after disruptions; and Service Portfolio Management is about managing the service offerings in line with business goals. Thus, the emphasis of Service Level Management on quality assurance through clear standards and regular evaluations makes it the correct answer.