Which of the following is true about user quotas in a filesystem?

User quotas in a filesystem are designed to manage and limit the amount of disk space a user can utilize. By establishing a quota, system administrators can ensure that no single user consumes an excessive amount of storage, which could lead to resource exhaustion and negatively impact other users or overall system performance. This mechanism is crucial in multi-user environments where equitable resource allocation is necessary to maintain system stability and performance.

The other options do not accurately reflect the fundamental function of user quotas. For example, options that mention filename extensions or preventing specific categories of files do not address the core purpose of quotas, which is strictly about limiting the amount of space a user can allocate on the filesystem as a whole. Additionally, a quota is not focused on limiting space consumed by a specific folder; it's generally applied on a per-user basis for their entire storage allocation rather than isolating it to individual directories.