Which of the following factors could necessitate an on-premises deployment?

Accessing on-prem data sources often requires an on-premises deployment due to security, compliance, or latency considerations. Many organizations have sensitive data that they prefer not to move to the cloud, either for regulatory reasons or to maintain greater control over their information. In such cases, deploying applications on-premises allows for easier integration and access to these local data sources without exposing them to potential vulnerabilities that could arise if they were hosted in a cloud environment.

While other factors such as customization of API policies, availability of managed services, and cost-effectiveness in training may influence deployment decisions, they do not inherently necessitate an on-premises setup. For instance, API policies can often be customized in cloud environments, and managed services are typically designed to simplify operations regardless of where the deployment occurs. Cost-effectiveness in training may also be feasible through different deployment strategies and doesn't directly correlate to an on-premises requirement. Thus, the direct need to connect securely and efficiently to on-prem data sources justifies an on-premises deployment.