Option 3: (A), (B), (C) and (D) -> All four statements correctly explain the concept of Aggregate Income from different perspectives. Statement (A) describes the income method where firms' revenue is distributed to factors of production as wages, rent, interest, and profits. Statement (B) represents the product/output method where national income equals the value of all goods and services produced. Statement (C) illustrates the expenditure method and circular flow of income where income spent becomes firms' revenue. Statement (D) correctly states that multiple methods exist to calculate aggregate income, not just expenditure method. Together, these statements comprehensively cover the circular flow of income and the three standard methods (Income, Product, and Expenditure) of measuring national income in an economy. -> correct