In a closed economy, there is no international trade, meaning exports and imports are zero. Therefore, aggregate demand is composed exclusively of three sectors: household consumption (C), private investment (I), and government spending (G). The sum of these three variables represents the total expenditure on goods and services produced within the domestic economy, excluding any external influences or foreign transactions.

The provided answer suggests that decreasing consumption and investment is a remedy for unemployment. However, standard Keynesian theory posits that unemployment is caused by deficient aggregate demand. Therefore, the Keynesian remedy typically involves increasing government spending or lowering taxes to stimulate consumption and investment, not decreasing them. This answer choice appears to contradict standard macroeconomic theory.

The multiplier is calculated as 1/(1-MPC). If the MPC increases, the denominator (1-MPC) decreases, which mathematically increases the value of the multiplier. The provided answer 'B' suggests an increase in the marginal propensity to save, which is incorrect because MPC and MPS are inversely related (MPC + MPS = 1). Thus, an increase in MPC must lead to a decrease in MPS.

The expenditure multiplier is defined as 1/(1-MPC). Since the sum of the marginal propensity to consume (MPC) and the marginal propensity to save (MPS) equals 1, it follows that 1-MPC equals MPS. Therefore, the multiplier can be expressed as 1/(1-MPC) or 1/MPS, making both options A and B mathematically equivalent representations.

In a closed economy without government intervention, the multiplier is defined as 1/(1-MPC). Since the sum of the marginal propensity to consume (MPC) and the marginal propensity to save (MPS) equals 1, the denominator (1-MPC) is equivalent to MPS. Thus, the multiplier is 1/MPS. This represents how an initial injection of investment spending leads to a larger total increase in national income through successive rounds of consumption.

The multiplier effect occurs because an initial injection of government spending becomes income for others, who then spend a portion of that income on consumption. This cycle repeats, creating a cumulative effect on aggregate demand that is greater than the initial government expenditure. The size of this effect depends on the marginal propensity to consume.

The Keynesian multiplier is defined as the ratio of a change in equilibrium output to an initial change in autonomous spending. It is calculated using the formula 1 / (1 - MPC). Given an MPC of 0.5, the calculation is 1 / (1 - 0.5), which equals 1 / 0.5, resulting in a multiplier of 2. This indicates that every unit of autonomous spending generates two units of total output in the economy.

The investment multiplier effect describes the process where an initial injection of investment spending circulates through the economy, creating additional rounds of consumption and income. Because each recipient of income spends a portion of it based on their marginal propensity to consume, the final increase in national income is a multiple of the original investment. This is a fundamental concept in Keynesian macroeconomics.

The multiplier is a fundamental concept in macroeconomics that measures the magnification effect of an autonomous change in spending (such as investment, government expenditure, or exports) on the final equilibrium level of national income. It quantifies how much total output changes for every unit change in an autonomous component of aggregate demand, reflecting the chain reaction of spending throughout the economy.

The multiplier effect describes how an initial change in spending leads to a larger final change in aggregate demand. In a downward scenario, reduced consumption or investment leads to lower income for others, who then reduce their own spending, creating a contractionary cycle. This process demonstrates the interdependence of income and expenditure within an economy, where initial shocks are amplified through successive rounds of spending reductions.