The shortcut key used for justifying a Microsoft Word document is:

🧠 Explanation:

Justifying a document aligns text evenly along both the left and right margins, giving it a neat, professional appearance. In Microsoft Word, the shortcut Ctrl + J is used to quickly apply this formatting without navigating through menus. “Used” is a past participle here, indicating the function assigned to the shortcut key. Alternatives for text alignment include Ctrl + L for left, Ctrl + R for right, and Ctrl + E for center alignment, but only Ctrl + J ensures equal spacing on both sides. This shortcut is essential for efficient document formatting and saves time during editing.