Growth of real GDP in the Czech Republic is at a historically low level. An economic summit in Prague invited the leading economists to pose a solution to the declining economic situation. Many of the economists in attendance subscribe to supply side economic theory. Their solution is to reduce the incredibly high marginal tax rate of 68% to 35%. The primary benefit of such a policy is:（）
A. higher levels of disposable income and ability to consume goods and services leading to higher GDP.
B. greater incentive for individuals to spend-their income on tax-deductible luxury items.
C. increased incentive for domestic investment leading to increased aggregate supply and GDP.
参考答案：C
解析：
Marginal tax rates affect the reward derived from additional work, investment, or saving, and are the most critical variable influencing consumer behavior. Reducing the marginal tax rate will provide incentives to work harder, invest wisely, and spend less time avoiding taxes.