Correct Answer: Sales revenue earned by a firm

Solution : The correct answer is (d) Sales revenue earned by a firm

Sales revenue earned by a firm is not included in the calculation of national income. National income measures the total income earned by individuals and businesses within a country's borders. While sales revenue is an important financial metric for businesses, it is not directly included in the calculation of national income. National income typically includes components such as wages and salaries, rental income, interest income, and profits earned by businesses.