The characteristic that is generally a mark of a developed country among the options provided is high per capita energy use. Developed countries typically have higher energy consumption per person due to more industrial activities, advanced technologies, and higher living standards.
The other options reflect characteristics more commonly found in developing countries:
- High levels of people farming to feed themselves suggest a reliance on subsistence agriculture, often seen in developing nations.
- Low literacy rate is typically associated with lower levels of education and opportunity, common in less developed countries.
- Low numbers of people living in cities or suburbs indicates a more rural population, which is often the case in developing nations where urbanization is not as pronounced.
Therefore, "high per capita energy use" is the correct choice.