Engineers and physicists dream of solving the world's energy supply problem by constructing power plants that would convert hydrogen to helium. Our Sun seems to have solved this problem. Choose the statement below that correctly identifies a major obstacle to this potentially environmentally clean mode of energy production. Choose one:
a. Hydrogen gas is not readily available on the Earth.
b. It currently takes so much energy to produce the high density and temperature required to fuse hydrogen to helium in the lab, that the energy we get out is less than we need to put in.
c. The amount of energy produced by converting an even tiny quantity of hydrogen to helium could not safely be controlled on Earth.
d. Being so close to the source of the resulting neutrinos would be fatal to life on Earth.
