Which file contains group account information?

The file that contains group account information in a Linux system is /etc/group. This file serves as a central repository for defining the various groups on the system and listing the users that belong to each group. Each line in this file represents a single group and includes fields such as the group name, password (if any), group identifier (GID), and a list of users associated with that group.

Understanding the structure of the /etc/group file is essential for managing user permissions and access within the system, as groups typically dictate what resources users can access. The other options provided do not serve this purpose. For instance, /usr/groups, /etc/grouplog, and /var/groupdata are not standard files in a Linux environment for holding group account information, and thus would not be usable for this purpose.