Explanation:

- Factor income: This includes wages, salaries, rent, interest, and profits generated by producing goods and services. It's part of national income.

- Rent: It's income received by property owners for the use of land or other resources. Rent is counted in national income as a return to one of the factors of production.

- Operating surplus: Operating surplus is the income from business operations outside of wages. It contributes to the national income.

- Transfer income: This includes pensions, unemployment benefits, and other forms of financial aid. Transfer income is not included in national income as they are not received for contributions to current production.

Correct answer:

- Transfer income