Your company has a Microsoft 365 subscription and uses Microsoft 365 Copilot Chat.

The requirement is specific: users must build and use declarative agents that can access work data (tenant data / organizational context). Microsoft’s licensing guidance for Copilot extensibility ties use of declarative agents to having the appropriate Copilot entitlement that enables tenant grounding and organizational data access. In Microsoft’s cost and licensing considerations for declarative agents, Microsoft states that to use a declarative agent, users must have a Microsoft 365 Copilot add-on license (or an equivalent Copilot Chat add-on path tied to eligible licensing). Therefore, among the provided options, the best recommendation is A.

Option B (Copilot Studio user license) is primarily about authoring/building agents in Copilot Studio, but it is not, by itself, the licensing prerequisite that grants end users the right to use those agents with full Microsoft 365 Copilot capabilities and work-data grounding inside the Microsoft 365 Copilot environment. Publishing/building can be separate from the end-user entitlement to use the agent with organizational context.

Option C (Copilot Chat pay-as-you-go) can enable usage-based access to declarative agents in some configurations, but the question asks for the best license recommendation for users who need work-data access through declarative agents. The Microsoft 365 Copilot add-on is the straightforward, fully supported entitlement for that scenario.