Which Azure service enables a consultant to obtain cross-tenant, role-based access to multiple clients' Azure environments?

Azure Lighthouse is the correct answer because it allows service providers to manage Azure resources across multiple customer tenants from their own tenant. This enables cross-tenant management with delegated access, making it ideal for consultants or managed service providers. Azure Arc extends Azure management to on-premises, multi-cloud, and edge environments, but doesn't primarily focus on cross-tenant access for service providers. Azure Advisor provides recommendations for optimizing Azure resources, and Azure Bastion provides secure and seamless RDP/SSH connectivity to virtual machines, neither of which addresses cross-tenant access for consultants.