Which is the best and the worst objects for the rescue workers to them to get energy?

combution engine

solar cell

human powered generator

hydroeletric power plant

fuel burning power plant

nuclear power plant

wind turbine

answer my
i need

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.