In the context of cloud delivery models, the term “trusted” typically refers to the level of security control and assurance that clients can expect. Among the options provided, the Public cloud delivery model is generally considered to be the least “trusted” in terms of security by clients using the service. This is because public clouds are shared environments where the infrastructure and services are owned and operated by a third-party provider and shared among multiple tenants. The multi-tenant nature of public clouds can introduce risks such as data breaches or other security incidents that might not be as prevalent in more controlled environments.

In contrast, Private clouds are dedicated to a single organization, providing more control over data, security, and compliance. Hybrid clouds combine both public and private elements, offering a balance of control and flexibility. Community clouds are shared between organizations with common goals and compliance requirements, offering a level of trust tailored to the group’s needs.

Therefore, while all cloud models come with their own security considerations and potential risks, the public cloud model is typically the one where clients have to place more trust in the provider’s security measures, as they have less control over the environment.

References: The information provided here is based on common cloud computing frameworks and security considerations, which are part of the foundational knowledge of Information Security Management Principles as outlined by BCS and supported by industry insights12.