The docker image pull command (or its shorthand docker pull) is the standard command used to download a Docker image from a container registry, such as the default Docker Hub. When docker image pull debian is executed, Docker contacts the registry, finds the image named "debian," and downloads its layers to the local machine. If no specific tag is provided, Docker defaults to pulling the image with the latest tag.

A. docker image init debian is an invalid command; init is not a valid subcommand for docker image.

C. docker image import debian creates a new filesystem image from the contents of a tarball, not from a remote repository.

D. docker image save debian is used to export an existing local image to a tar archive; it does not download an image.

1. Docker Inc.

Official Docker Documentation

docker image pull command reference. The documentation states: "Pull an image or a repository from a registry... Most of your images will be created on top of a base image from Docker Hub."

2. Turnbull

J. (2018). The Docker Book: Containerization is the new virtualization (2nd ed.). Chapter 3

"Working with Docker images

" explicitly demonstrates using docker pull to download images from Docker Hub.

3. Massachusetts Institute of Technology (MIT) OpenCourseWare

6.033 Computer System Engineering

Spring 2018. Lecture 20

"Containers

" discusses the Docker ecosystem

including the role of Docker Hub and the pull command for retrieving images.