Option 1 -> Social security contributions are transfer payments, not separately counted in National Income to avoid double counting.
Option 2 -> Maintenance expenditure is intermediate consumption, not capital formation, hence excluded.
Option 3 -> Adding a floor is capital formation (investment), which increases productive capacity and is included in National Income.
Option 4 -> Interest on personal loans is a transfer payment, not income from productive activity.
Hence, Option 3: Expenditure on adding a floor to the building -> This represents Gross Fixed Capital Formation (GFCF) as it creates a new asset and adds to the productive capacity of the economy. Unlike maintenance (which only preserves existing assets), construction of new structures or additions to existing ones is treated as investment and forms part of National Income calculation. It contributes to GDP and hence National Income. -> correct