The correct option is (B) An error of principle.

Reasoning: The provided context (entry i) illustrates the rectification for this specific scenario where 'Wages paid for installation of machinery' was wrongly debited to the Wages Account. The rectification entry transfers this amount to the Machinery Account.

Wages paid for the installation of an asset are a Capital Expenditure and must be added to the cost of the machinery (Real Account). However, debiting it to the Wages Account treats it as Revenue Expenditure (Nominal Account). An error that violates the fundamental accounting principle of distinguishing between Capital and Revenue expenditure is called an Error of Principle.