How can Google Docs support collaborative writing projects?

Google Docs enhances collaborative writing projects primarily through the feature that enables simultaneous editing by multiple users. This functionality allows numerous contributors to work on a document in real-time, making it easy for them to share ideas, provide immediate feedback, and make alterations to the text without needing to send multiple versions of the file back and forth. Users can see each other's changes as they happen, resulting in a more dynamic and interactive writing process.

This real-time collaboration is invaluable for group projects, as it fosters teamwork and improves communication. Additionally, users can leave comments, suggest edits, and engage in conversations directly within the document, further enhancing the collaborative experience.

The other options do not effectively support collaborative projects: allowing edits from a single user limits collaboration, automatic grading does not apply to the writing process itself, and converting documents into PDFs is more about sharing the finished product rather than facilitating the collaborative writing process.