This answer allows the accounting user to run the /opt/acc/report command as root on any host without entering a password. The % sign indicates that accounting is a group name, not a user name. The ALL keyword means any host, any user, and any command, depending on the context. The NOPASSWD tag overrides the default behavior of sudo, which is to ask for the user's password.
The other answers are incorrect for the following reasons:
A) accounting localhost=/opt/acc/report
This answer only allows the accounting user to run the command on the localhost, not on any host.
This answer also requires the accounting user to enter their password, which is not specified in the question.
B) accounting ALL=/opt/acc/report
This answer only allows the accounting user to run the command as themselves, not as root.
This answer also requires the accounting user to enter their password, which is not specified in the question.
D) accounting /opt/acc/report= (ALL) NOPASSWD: ALL
This answer has an invalid syntax, as there should be no space between the equal sign and the parentheses.
This answer also grants too much privilege to the accounting user, as it allows them to run any command as any user without a password.

The command that will display the operating system is uname -o. This command uses the uname tool, which is used to print system information such as the kernel name, version, release, machine, and processor. The -o option stands for operating system, and prints the name of the operating system implementation (usually GNU/Linux).
The other options are not correct commands for displaying the operating system. The uname -n command will display the network node hostname of the system. The uname -s command will display the kernel name of the system. The uname -m command will display the machine hardware name of the system. Reference: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 1: Exploring Linux Command-Line Tools; uname(1) - Linux manual page

The command hostnamectl set-hostname Comptia-WebNode -H [email protected] sets the hostname of the web server to Comptia-WebNode and connects to the server using the SSH protocol and the root user. This is the correct way to complete the requirement. The other options are incorrect because they either display the current hostname status (hostnamectl status), set an invalid hostname (hostnamectl set-hostname "$(perl -le "print" "A" x 86)"), or set a transient hostname that is not persistent (hostnamectl set-hostname Comptia-WebNode --transient). Reference: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 9: Managing System Components, page 291.

The most likely reason the timer will not start is that the checkdiskspace.timer should be configured to allow manual starts. By default, systemd timers do not allow manual activation via systemct1 start, unless they have RefuseManualStart=no in their [Unit] section. This option prevents users from accidentally starting timers that are meant to be controlled by other mechanisms, such as calendar events or dependencies. To enable manual starts for checkdiskspace.timer, the administrator should add RefuseManualStart=no to its [Unit] section and reload systemd.
The other options are not correct reasons for the timer not starting. The checkdiskspace.timer unit does not need to be enabled via systemct1 enable, because enabling a timer only makes it start automatically at boot time or after a system reload, but does not affect manual activation. The timers.target does not need to be reloaded to get the new configuration, because reloading a target only affects units that have a dependency on it, but does not affect manual activation. The checkdiskspace.timer does not need to be started using the sudo command, because the administrator is already running systemct1 as root, as indicated by the # prompt. Reference: systemd.timer(5) - Linux manual page; systemct1(1) - Linux manual page