Correct Answer: Sales tax

Solution : The correct answer is (d) Sales tax.

Sales tax is not included in the calculation of national income. National income refers to the total income earned by individuals, businesses, and the government within a country in a given period. It is a measure of the country's economic activity and includes various sources of income.

Sales tax, on the other hand, is a tax imposed on the sale of goods and services. It is not considered as income earned by individuals, businesses, or the government and therefore is not included in the calculation of national income. Sales tax is typically treated as a tax liability rather than as part of the income generated by economic activities.