After installing a new package, in which directory are you most likely find its configuration file?

/lib contains shared library files and kernel modules required for booting and running binaries, not configuration files.

/conf is not a standard directory in the Linux Filesystem Hierarchy Standard and does not typically exist on a Linux system.

According to the Filesystem Hierarchy Standard, /etc is designated for host-specific system configuration files. Package managers such as apt and yum install application configuration files here by convention (e.g., /etc/nginx/nginx.conf, /etc/ssh/sshd_config). This makes /etc the first place to look for a newly installed package's configuration.

/usr contains user-space programs, documentation, and read-only data, but not host-specific configuration files.

/opt is reserved for optional or third-party self-contained software packages; while some packages store data here, standard configuration still goes in /etc.