HPE GreenLake for Private Cloud Enterprise is the ideal solution as it directly addresses all the customer's requirements. It provides an on-premises private cloud, which satisfies the government agency's need for tight data residency and control. The solution offers a self-service, catalog-based portal for provisioning virtual machines, containers, and bare metal, delivering a public cloud-like experience. Finally, the entire HPE GreenLake platform operates on a consumption-based, pay-per-use model, which aligns with the customer's preference for an Operational Expenditure (OpEx) financial model instead of a large upfront capital investment.

B. Hyperscale public-cloud-only: This fails the tight data residency requirement, as data would be in the provider's data center, potentially subject to foreign laws, not the agency's own on-premises location.

C. CapEx tape library upgrade: This is a capital expenditure (CapEx), the opposite of the required OpEx model, and it does not provide catalog-based provisioning for cloud services.

D. Branch Wi-Fi refresh: This is a networking solution and is irrelevant to the core requirements of data residency for applications and catalog-based provisioning of cloud compute resources.

1. HPE GreenLake for Private Cloud Enterprise Datasheet (a50004532enw, March 2023):

Page 1: "Run it in your data center or colocation facility of choice, fully managed for you by HPE." (Supports data residency).

Page 1: "Self-service for VMs, containers, and bare metal." (Supports catalog-based provisioning).

Page 1: "Consumption-based..." (Supports OpEx model).

2. HPE GreenLake for Private Cloud Enterprise Solution Brief (a50004533enw, March 2023):

Page 2, "Your cloud, your way": "HPE GreenLake for Private Cloud Enterprise delivers a cloud-native experience to your apps and data wherever they live—in your data centers, in a colocation facility, or at the edge." (Supports data residency).

Page 3, "Self-service agility for developers": "Provision VMs and bare metal in just a few clicks from a simple catalog of instance types..." (Supports catalog-based provisioning).

3. HPE GreenLake Edge-to-Cloud Platform Official Documentation:

"What is HPE GreenLake?" section: "The HPE GreenLake platform delivers the cloud experience... with a pay-per-use model." (Supports OpEx model). This is a foundational principle of the entire GreenLake portfolio.