What is a measurable feature that illustrates a country's level of development?

A social indicator is a measurable feature that provides insight into a country's level of development by assessing aspects of the population's well-being. These indicators often include metrics such as literacy rates, life expectancy, and access to education and healthcare. They help to paint a more complete picture of the human aspect of development, beyond just economic measures.

For example, a country with high literacy rates and good healthcare access may indicate a developed society, even if its economic growth is not as rapid as another nation. Social indicators are crucial for understanding how development impacts individuals' quality of life, making them essential for assessing overall societal progress.

While economic growth, political stability, and infrastructure quality are important factors in determining levels of development, they do not directly measure the social conditions and well-being of people in the same way that social indicators do. Each of these other choices may contribute to development but is not a direct measurement of human welfare and societal progress.