Option 1 -> Aggregate supply refers to total goods and services produced, not specifically the income level at full employment.
Option 2 -> Aggregate demand refers to total spending in the economy, not the income level where all factors are employed.
Option 3 -> Full employment level is the income level where all factors of production (land, labor, capital, entrepreneurship) are optimally utilized.
Option 4 -> Total income is a measure of all earnings but doesn't specify the employment status of factors.
Hence, Full employment -> Full employment level of income is that equilibrium level where all available factors of production are fully and efficiently employed in the production process. At this level, there is no involuntary unemployment and resources are optimally utilized to produce maximum output. This represents the economy's potential output. -> correct