The Union Budget classifies government expenditure under two broad categories: Plan Expenditure and Non-Plan Expenditure.
Plan Expenditure includes the expenditure on the government`s plan schemes, which are designed to achieve specific development goals.
Non-Plan Expenditure includes all other government expenditure that does not come under Plan Expenditure.
The components of Non-Plan Expenditure include, but are not limited to:
1. Defence expenditure
2. Interest payments
3. Salaries and pensions
4. Subsidies
Therefore, the correct answer is "1, 2, 3, and 4".