VM-Series bootstrapping allows for automated initial configuration. Several methods exist for installing licensed content.  

Why A, B, and D are correct:

A. Panorama 10.2 or later to use the content auto push feature: Panorama can push content updates to bootstrapped VM-Series firewalls automatically, streamlining the process. This requires Panorama 10.2 or later.  

B. Complete bootstrapping and either Azure Blob storage or Amazon S3 bucket: You can store the content updates in cloud storage (like S3 or Azure Blob) and configure the VM-Series to retrieve and install them during bootstrapping.

D. Custom-AMI or Azure VM image, with content preloaded: Creating a custom image with the desired content pre-installed is a valid approach. This is particularly useful for consistent deployments.

Why C and E are incorrect:

C. Content-Security-Policy update URL in the init-cfg.txt file: The init-cfg.txt file is used for initial configuration parameters, not for direct content updates. While you can configure the firewall to check for updates after bootstrapping, you don't put the actual content within the init-cfg.txt file.

E. Panorama software licensing plugin: The Panorama software licensing plugin is for managing licenses, not for pushing content updates during bootstrapping.

Palo Alto Networks References:

VM-Series Deployment Guides (AWS, Azure, GCP): These guides detail the bootstrapping process and the various methods for installing content updates.  

Panorama Administrator's Guide: The Panorama documentation describes the content auto-push feature.

These resources confirm that Panorama auto-push, cloud storage, and custom images are valid methods for content installation during bootstrapping.