How can you create an image from a running container?

Creating an image from a running container is accomplished with the docker commit [container_id] [new_image_name] command. This command takes the current state of a specified container and saves it as a new image. It captures all changes made to the container after it was started, including any new files created, modifications to existing files, and installed packages.

When you run this command, Docker generates an image that reflects the container's filesystem at that particular moment. This is especially useful for creating a new image based on a container that has been modified during development or testing, allowing you to preserve those changes for future use or distribution.

The other options pertain to different functionalities. For example, exporting a container using docker container export creates a tar archive of the container’s filesystem rather than an image. Similarly, docker save is used to save an image to a tar archive, and docker image build is focused on building images from a Dockerfile, not from a running container's state.