Correct Answer: Capital gains

Solution : The correct answer is d) Capital gains.

Capital gains are not included in the calculation of national income. National income measures the total income earned by individuals, businesses, and other entities within a country during a specific time period.

Capital gains are the profits realized from the sale of assets, such as stocks, real estate, or artwork. They are not considered as part of national income because they are not generated through current production or economic activity.