Which feature allows an administrator to implement master copies of virtual machines to create ready-for-use virtual machines?

The correct choice is templates, which are a fundamental feature in VMware environments for streamlining the creation of virtual machines. Templates serve as a master copy that contains a pre-configured virtual machine, including its operating system, applications, and settings. This allows administrators to quickly deploy new virtual machines that already have the desired configurations and software without having to set them up individually each time.

Templates are particularly useful in managing large environments, as they ensure consistency across virtual machine deployments, reduce the risk of human error, and accelerate the provisioning process. When a template is used, an administrator can create multiple clones of the template, which can be powered on immediately and utilized in a variety of use cases such as development, testing, or production environments.

In contrast, the other options do not fulfill this specific purpose. Custom attributes are used for tagging and categorizing virtual machines but do not provide a mechanism for creating new VMs. Snapshots are used to capture the state of a virtual machine at a certain point in time, allowing for rollback capabilities, but they do not create new instances. Resource pools are a way to allocate and manage resources among virtual machines but do not facilitate the cloning or creation of VMs from a master image.