Which key is commonly used to erase letters on the keyboard?

Correct answer: Backspace

The Backspace key removes the character immediately to the left of the insertion cursor when text is being edited, so option C is correct. Enter starts a new line or confirms an action, Shift changes the case or types an alternate symbol, and Caps Lock changes continuous letter capitalization. The Delete key can remove the character to the right, so Backspace and Delete should not be confused.