To achieve alignment, what must be measurable by the service level agreement?

The correct choice is the promises in vision and mission statements because service level agreements (SLAs) are designed to specify expectations and standards that should be measurable. These agreements articulate what the service provider commits to deliver in terms of services. When the promises made in an organization's vision and mission statements are integrated into an SLA, they create a framework where the organization's core objectives and values are translated into measurable outcomes. This ensures that the service delivery meets the expectations set forth in those foundational documents, thereby achieving alignment between the organization's strategic goals and operational practices.

While the other options contain elements that are important to the overall performance and quality of service, they do not inherently serve as the primary basis for measurable commitments in an SLA. Financial performance is more of an overall organizational metric rather than a specific service delivery measure. Customer feedback is valuable, but it is typically used for assessment after the service is provided rather than as a metric laid out in advance. Lastly, the experience of support staff, while crucial for service quality, is also not a direct element of what an SLA should measure; rather, it's more about how staff competence translates into customer service quality.