What is most characteristic of a society having a caste system

b.

developed countries have tended to improve the environment, while developing countries have tended to damage it.

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.