Answer : 1. "control "
Explanation :

1. The Control key, also called the Ctrl key, is a modifier key found on most computer keyboards. It's usually located in the lower left part of the keyboard, next to the Caps Lock and Tab keys.

2. The Control key is used in combination with other keys to perform various keyboard shortcuts. For example, pressing Ctrl+C copies the selected text to the Clipboard, pressing Ctrl+V pastes text from the Clipboard, and pressing Ctrl+S saves the current document.

3. Various uses of control keys-

Ctrl+C: Copy

Ctrl+V: Paste

Ctrl+X: Cut

Ctrl+Z: Undo

Ctrl+Y: Redo

Ctrl+A: Select all

Ctrl+B: Bold

Ctrl+I: Italic

Ctrl+U: Underline

Ctrl+S: Save

Ctrl+O: Open

Ctrl+N: New

Ctrl+P: Print

Ctrl+F: Find

Ctrl+H: Replace

Pressing Ctrl+Shift+Esc opens the Task Manager.

Pressing Ctrl+Alt+Delete opens the Windows Security screen.