Final answer:
The correct command is 'docker tag httpd:latest httpd:old' which uses the 'docker tag' command to create a new tag for an existing image in Docker.
Step-by-step explanation:
The correct command to tag an image called 'httpd:latest' to a new name called 'httpd:old' is A) docker tag httpd:latest httpd:old. The 'docker tag' command is used for creating a tag TARGET_IMAGE that refers to SOURCE_IMAGE. By using this command, you create a reference to the image with the new tag without changing the original image. Docker does not have a 'rename' command for images, which makes options B and D incorrect. The order in the command C is reversed; the correct syntax requires the source name first followed by the new tag name.