Which of the terrestrial planets is closest to the sun?

Mercury is the closest planet to the sun. Earth is the closest planet to the sun that has life on 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.