Greater control is a key advantage of a private cloud. A private cloud is dedicated to a single organization and may be hosted on-premises or by a third-party provider. Because the environment is not shared in the same way as a public cloud, the organization typically has more control over security policies, compliance requirements, hardware choices, network architecture, data placement, access control, and change management.
The CompTIA Network+ N10-009 objectives include cloud concepts such as public cloud, private cloud, hybrid cloud, and cloud characteristics. Private cloud is often chosen when an organization has strict regulatory, security, performance, or customization requirements. It can provide cloud-like features while still allowing more direct governance over infrastructure and data.
On-demand scalability is strongly associated with cloud computing in general and is especially common in public cloud environments, but it is not the best distinguishing advantage of private cloud. Public accessibility describes a public cloud or internet-facing service, not a private cloud advantage. No up-front costs is more closely associated with public cloud consumption models. Therefore, greater control is the best answer.