Explanation:

- Subsidized Lunch: Government spending on providing meals at reduced prices in schools. It is a transfer payment, not part of National Income.

- Old-age Pension: Payments made to retirees, a form of social security transfer. Not included in National Income as they are transfer payments.

- Free Medical Facilities: Provision of health services without direct payment. It is a government transfer, not part of National Income.

- Construction of a House: Represents tangible production activity that contributes to the Gross Domestic Product, included in National Income estimation.

The correct answer is Old-age Pension, since it is not included in the estimation of National Income.