The measure of a country`s economic growth is often gauged through different economic indicators.

Option 1: Gross Domestic Product (GDP) calculates the value of goods and services produced within a country. However, GDP does not consider income distribution or population.

Option 2: Net Domestic Product (NDP) considers the GDP minus depreciation. But like GDP, it does not take into account income distribution or population.

Option 3: Net National Product (NNP) measures the value of goods and services produced by residents of a country, regardless of their location. NNP doesn`t account for income distribution and population size.

Option 4: Per Capita Real Income represents the income of an individual in a country, after adjusting for inflation. This measure usually provides a more accurate picture as it takes into account population size. High per capita income indicates higher economic growth and living standards.

Thus, among the options given, the most appropriate measure to gauge a country`s economic growth is Option 4: Per Capita Real Income, since it takes into account both economic production and population size.