Dividends are taxed at a preferential rate in Canada due to the dividend tax credit, which reduces the effective tax rate on dividend income. This is intended to prevent double taxation because corporations have already paid taxes on their profits before distributing dividends to shareholders.

Why Other Options are Incorrect:

B . Dividends from preferred shares are ineligible for the dividend tax credit: This is incorrect; dividends from both common and preferred shares are eligible for the dividend tax credit.

C . Stock dividends are treated differently than regular cash dividends for tax purposes: Stock dividends are generally taxed similarly to cash dividends.

D . Reinvested dividends are non-taxable to the shareholders: Reinvested dividends are taxable in the year they are earned, even if reinvested.

Reference: CSC Volume 2, Chapter 24, 'Taxation of Dividend Income' discusses the tax treatment of dividends and the dividend tax credit.