The correct answer is: D. NNP + Depreciation.
GNP stands for Gross National Product. It is the market value of all final goods and services produced in a country in a given year, plus net income from abroad. NNP stands for Net National Product. It is the market value of all final goods and services produced in a country in a given year, minus depreciation. Depreciation is the decrease in the value of capital goods over time due to wear and tear.
Therefore, GNP can be defined as NNP plus depreciation.
Option A is incorrect because NNP is already included in GNP.
Option B is incorrect because exports are not included in GNP. GNP measures the value of goods and services produced within a country, not the value of goods and services that are sold to other countries.
Option C is incorrect because indirect taxes are not included in GNP. Indirect taxes are taxes that are levied on goods and services, such as sales taxes and value-added taxes. These taxes are not included in GNP because they are not considered to be part of the value of the goods and services that are being produced.