Which of the following occupies less memory when saving an MS-Word file?

The correct option is .docx.

Explanation:

1. File Format Differences:
- .doc: This is the legacy binary file format used by Microsoft Word 2003 and earlier versions. Binary formats store uncompressed structured data, which leads to larger file sizes.

2. The OpenXML Advantage:
- .docx: Introduced in Microsoft Word 2007, this format is based on the Office OpenXML standard. A .docx file is essentially a compressed zip archive containing XML files and embedded media assets. Because the content is automatically compressed using ZIP compression, it consumes significantly less disk space/memory compared to the older .doc format.

3. Other Formats:
- .docm: This format also uses OpenXML compression, but it supports embedded VBA (Visual Basic for Applications) macros, which can add extra file overhead.
- .docc: This is not a standard Microsoft Word file extension.

Therefore, .docx occupies the least memory when saving a standard Microsoft Word document.