Final answer:
Life expectancy is one of the key indicators of a country's development, offering insights into the health and quality of life. Alongside this, literacy rate and GDP per capita serve as important measures that reflect a nation's educational attainment and economic prosperity respectively.
Step-by-step explanation:
One of the three factors indicative of a country's development is life expectancy. Life expectancy is the average age to which a person in a given population is expected to live. It is a vital indicator as it reflects the overall health and wellbeing of a population. Higher life expectancy is often seen in more developed nations due to better healthcare, nutrition, and living conditions.
Other important indicators of a country's development include the literacy rate, which is the percentage of people aged 15 and above who can read and write. A high literacy rate suggests a nation's commitment to education and correlates with other economic and social benefits. Moreover, the Gross Domestic Product (GDP) per capita is a measure of a country's economic output that accounts for its population. It provides an overview of the prosperity and standard of living for residents of a nation.
These indicators are used within broader measures such as the Human Development Index (HDI), which combines life expectancy, educational levels, and income to provide a more composite picture of human development in a country.