Explanation:

The command that will allow the administrator to determine the first command that is executed inside the container right after it starts is docker inspect <container_id>. This command will display detailed information about the container, including its configuration, state, network settings, mounts, and logs. One of the configuration fields is "Entrypoint", which shows the command that is executed when the container is run. The entrypoint can be specified in the Dockerfile or overridden at runtime using the --entrypoint option.

To delete a file from a Git repository, the administrator can use the command git rm app.conf (D). This will remove the file "app.conf" from the working directory and stage it for deletion from the repository. The administrator can then commit the change with git commit -m "Delete app.conf" to finalize the deletion. The other commands will not delete the file, but either tag, commit, or checkout the file. References:
* [CompTIA Linux+ Study Guide], Chapter 10: Working with Git, Section: Deleting Files with Git
* [How to Delete Files from Git]