By default, which directories contents will be copied to a new user’s home directory when the account is created, passing the -m option to the useradd command?

Answer: /etc/skel

Explanation:
From the man pages:
The skeleton directory, which contains files and directories to be copied in the users home directory, when the home directory is created by useradd. The skeleton directory is defined by the SKEL variable in /etc/default/useradd or, by default, /etc/skel.