In the vi (or Vim) text editor, which symbol is used to backspace over typing errors while entering text?

Introduction / Context:
While editing in vi/Vim, you often need to correct mistakes quickly as you type. The question asks specifically for a symbol that backs up over typing errors. Understanding vi's Insert-mode editing keys prevents needless mode switches and speeds up everyday text manipulation.

Given Data / Assumptions:

• You are in Insert mode (press Esc to leave, i to enter).
• You want to erase characters you just typed.
• Options presented are printable symbols (for example, '!', '$').

Concept / Approach:
In vi/Vim, the normal way to correct typing errors in Insert mode is to press the Backspace key, which often generates the control character ^H. Some terminal configurations may also allow Control-H to act as backspace. These are control keys, not printable symbols. Therefore none of the listed punctuation characters perform the backspace function in vi's Insert mode by default.

Step-by-Step Solution:

Verification / Alternative check:
Run 'stty -a' in the terminal to confirm which control character is mapped as erase (commonly ^H or ^?). In Vim, ':help backspace' documents behavior and configuration that ensures Backspace works as expected in Insert mode.

Why Other Options Are Wrong:

• '!': Shell history expansion in some shells; not a vi backspace.
• '$': End-of-line motion in many contexts, not deletion.
• '#': Not a backspace key in vi.
• '@': Macro register invocation in Normal mode; not a backspace.

Common Pitfalls:
Confusing Normal-mode commands with Insert-mode editing, or expecting printable symbols to perform control functions without custom mappings. Also, terminal misconfiguration can disable Backspace unless 'backspace' option is set in Vim.

Final Answer:
None of the above