Explanation/Reference:

Explanation
The useradd command in Linux is used to create new user accounts on the system1. The -m option tells the command to create the user's home directory as /home/username and copy the files from /etc/skel directory to the user's home directory2. The /etc/skel directory contains the default configuration files for new users3.
Therefore, the command useradd -m tux will add the new user tux and create the user's home directory with default configuration files. The other options are either invalid or do not create the user's home directory.
References:
* Linux Essentials Version 1.6 Objectives, Topic 1.4: Command Line Basics, Subtopic: Basic Shell Commands
* Linux Essentials Version 1.6 Exam Preparation Guide, Section 1.4: Command Line Basics, Page 16
* Linux useradd Command Tutorial for Beginners (15 Examples)

The dmesg command is used to display the messages from the kernel that are stored in a ring buffer. A ring buffer is a fixed-size data structure that overwrites the oldest entries when it is full. Therefore, the dmesg command might not display older information because it was overwritten by newer information. The dmesg command is useful for troubleshooting system issues and checking hardware information. The dmesg command is not used to trace the execution of a command, send messages to user sessions, or output the system journal. Those functions are performed by other commands such as strace, write, and journalctl respectively. Reference: : [dmesg] : [Ring buffer] : [strace] : [write (Unix)] : [journalctl]4)

The correct command to change the ownership of the file doku.odt to a new owner named tux is chown tux doku.odt. This command uses the chown command, which stands for change owner, followed by the name of the new owner and the name of the file as arguments. The chown command allows you to change the user and/or group ownership of a given file, directory, or symbolic link12. The other options are incorrect because they use different commands or syntax that do not change the ownership of the file. For example:
Option A uses the chmod command, which stands for change mode, and is used to change the permissions of files and directories, not the ownership3.
Option B uses the newuser command, which is used to create a new user account, not to change the ownership of a file4.
Option D uses the transfer command, which is not a valid Linux command.
Option E uses the passwd command, which is used to change the password of a user account, not the ownership of a file5.