Solution
Option 1 -> Change in consumption is a result of the process, not the mechanism itself.
Option 2 -> Change in investment is a type of autonomous spending, not the amplification mechanism.
Option 3 -> These are assumptions in simplified models, not the cause of output magnification.
Option 4 -> The multiplier mechanism is the process that amplifies changes in autonomous spending.
Hence, Multiplier Mechanism -> When autonomous spending changes (such as investment, government spending, or exports), it triggers a chain reaction through the economy. The initial spending becomes income for recipients, who then spend a portion based on their marginal propensity to consume (MPC). This spending becomes income for others, who also spend a portion, and so on. The multiplier effect is calculated as 1/(1-MPC) or 1/MPS. For example, if MPC is 0.8, the multiplier is 5, meaning a 500. This mechanism explains why small changes in autonomous spending can cause large changes in total output -> correct