Which factor is most effective in promoting a fairer distribution of income?

Explanation

Option A refers to indirect taxes, which tend to be regressive and do not reduce income inequality. Option B, raising managers' pay, can widen income gaps. Option C, increasing progressive taxation, helps redistribute wealth by taxing higher incomes at greater rates, thus encouraging a more equitable income distribution. Option D, inflation, generally affects all income groups but does not inherently promote fairness in income distribution.