A custom image is a snapshot of a configured instance's boot disk. The standard OCI practice for deploying multiple, identical systems is to first launch a base instance, install all necessary applications, apply configurations, and then create a custom image from it. This "golden image" can then be used to launch any number of new instances that are exact clones of the original. This method encapsulates all setup work into a reusable template, ensuring consistency and representing the most minimal effort for subsequent deployments.

A. Bring your own image: This is primarily for migrating existing on-premises or third-party cloud virtual machines to OCI, not for creating new, identical instances within OCI itself.

B. Select an image from the OCI Marketplace: Marketplace images are vendor-provided templates. While useful, they would likely still require your own specific customizations before they could be considered "identical" for your needs.

C. Use Oracle-provided images: These are base operating system images. Using them would require you to manually configure each new instance from scratch, which is the opposite of minimal effort.

1. Oracle Cloud Infrastructure Documentation, "Managing Custom Images": "After you've installed software, applied updates and patches, and configured an instance to meet your needs, you can create a custom image of the instance's boot disk. You can then use the custom image to launch other instances that have the same customizations, configuration, and software." This directly describes the process of using custom images to create identical instances.

2. Oracle Cloud Infrastructure Documentation, "Overview of Images": This document defines the different image types. It clarifies that Oracle-provided images are basic templates, Marketplace images are from partners, and Custom Images are "images that you create from your running instances." This distinction highlights why custom images are the correct choice for this specific use case.

3. Oracle Cloud Infrastructure Documentation, "Creating an Image": "You can create a custom image of an instance's boot disk and use it to launch other instances. Instances that you launch from your image include the customizations, configuration, and software installed when you created the image." This reinforces that custom images are the mechanism for replicating a configured state with minimal effort.