To determine which option allows for accessing, editing, storing, and collaborating on documents online, let's analyze each option:

1. Memory Stick: This is a type of portable storage device used primarily for transferring data, but it does not provide online document collaboration or editing features.
2. Google Drive: Google Drive is a cloud-based storage solution that not only allows users to store documents but also offers features to access, edit, and collaborate on these documents in real time online. It integrates with Google Docs, Sheets, and Slides, which are online editing tools.
3. Hard Disk: A hard disk is a hardware component used for storing data within a computer. It does not have inherent online capabilities for document collaboration.
4. Pen Drive: Similar to a memory stick, a pen drive is a portable storage device used to transfer data; it does not facilitate online document editing or collaboration.

Thus, the correct answer is that Google Drive helps in accessing, editing, storing, and allowing collaboration on documents online. Other options like Memory Stick, Hard Disk, and Pen Drive function mainly as storage devices without providing online collaboration features.