A. Modifier
B. Adjustment
C. Function
D. All of these
🧠 Explanation:
- **Ctrl**, **Shift**, and **Alt** are known as **modifier keys** on a keyboard.
- They don’t perform any function on their own but modify the action of other keys when used in combination.
- Examples include shortcuts like Ctrl+C (copy), Shift+Arrow (select text), and Alt+Tab (switch windows).
- Modifier keys are essential for productivity, especially in software like Microsoft Office, Photoshop, and web browsers.