PWD",C.pwd##ComprehensiveExplanation:
##ThecommandsthatwillprintthecurrentworkingdirectorywhenusingaBashshellareecho"{PWD}" and pwd.
The echo command will print the value of the PWD variable, which is set by the shell to the current working directory. The pwd command will print the name of the current working directory. The WD variable is not a standard shell variable and may not be defined. The printwd command is not a valid Linux command. The pwd variable is not the same as the PWD variable and may not be defined. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.1: Work on the command line, echo command, pwd command

Systemd is a system and service manager for Linux systems, and it can manage the mounting and unmounting of file systems. Systemd can automatically create and start mount units for file systems that are listed in /etc
/fstab or are known to the system. Mount units are unit files that encode information about a file system mount point controlled and supervised by systemd. Mount units must be named after the mount point directories they control, and they have the suffix .mount. For example, the mount point /home must be configured in a unit file home.mount.
Systemd can also handle file systems that are neither listed in /etc/fstab nor known to the system, but are mounted manually by the user. In this case, systemd automatically generates a transient mount unit and monitors the mount point without changing it. A transient mount unit is a unit that is created dynamically and temporarily, and is not backed by a unit file on disk. A transient mount unit has the same name and properties as a regular mount unit, but it is not persistent across reboots. Systemd does not interfere with the manual mount, and does not unmount it unless explicitly requested by the user. The user can use the mount command or the systemd-mount command to create a manual mount, and the umount command or the systemd-umount command to remove it. The user can also use the systemctl command to inspect and control the transient mount unit. For example, to show the status of the transient mount unit for the mount point /mnt, use the following command:
systemctl status mnt.mount
References:
systemd.mount - freedesktop.org
systemd-mount - freedesktop.org
How to name systemd mount unit properly? - Server Fault
Working with Systemd Mount Units - Pluralsight

The mount command is used to attach a filesystem to a directory on the system, which is called a mount point.
The mount command requires the device name or the UUID of the filesystem as the first argument, and the mount point as the second argument. Optionally, the mount command can also take some options, such as the filesystem type, the mount options, and the label. The syntax of the mount command is:
mount [options] device mountpoint
In this question, the device name of the CD-ROM is /dev/sr0, and the mount point is /mnt/cdrom. Therefore, the correct command to mount the CD-ROM is:
mount /dev/sr0 /mnt/cdrom
This command will mount the CD-ROM as a read-only filesystem with the type iso9660, which is the standard format for optical discs. The mount command can automatically detect the filesystem type and the mount options, so there is no need to specify them explicitly. However, if you want to specify them, you can use the -t and -o options, respectively. For example, the following command is equivalent to the previous one:
mount -t iso9660 -o ro /dev/sr0 /mnt/cdrom
The other options are not correct because:
* A. mount /dev/cdrom /mnt/cdrom: This command may work on some systems, but it is not guaranteed to be correct. The /dev/cdrom is usually a symbolic link to the actual device name of the CD-ROM, which can vary depending on the system. For example, on some systems, the /dev/cdrom may point to
/dev/sr0, but on others, it may point to /dev/scd0 or /dev/hdc. Therefore, it is better to use the actual device name of the CD-ROM, which can be found by using the lsblk or the dmesg command.
* C. mount -t cdrom /dev/sr0 /mnt/cdrom: This command is not valid because cdrom is not a valid filesystem type. The filesystem type for optical discs is iso9660, not cdrom. The mount command will fail with an error message saying:
mount: unknown filesystem type 'cdrom'
* D. mount -l cdrom /dev/sr0 /mnt/cdrom: This command is not valid because -l is not a valid option for the mount command. The -l option is used to list all the mounted filesystems, not to mount a filesystem.
The mount command will fail with an error message saying:
mount: can't find /dev/sr0 in /etc/fstab
* E. mount -f /dev/sr0/mnt/cdrom: This command is not valid because it is missing a space between the device name and the mount point. The mount command requires two separate arguments for the device name and the mount point, separated by a space. Also, the -f option is used to fake the mount operation, not to perform the actual mount. The mount command will fail with an error message saying:
mount: /dev/sr0/mnt/cdrom: mount point does not exist.
References:
How to mount cdrom in Linux - Learn Linux Configuration
Mount CD-ROM in Linux using Command Line - nixCraft
Mounting the CD or DVD (Linux) - IBM