HashiCorp Vault enables authentication mechanisms using the vault auth enable command followed by the name of the authentication method. To enable AppRole authentication, the correct command is vault auth enable approle. AppRole is specifically designed for machine-to-machine authentication, making it ideal for CI/CD tools like Jenkins. It allows applications to authenticate securely using role IDs and secret IDs instead of static credentials. The other options do not follow Vault CLI syntax and would result in command errors. Enabling AppRole during the Build and Test stage ensures that secrets are accessed securely and dynamically, supporting least-privilege access control and reducing the risk of credential leakage across the DevSecOps pipeline.