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.
a. it is difficult to achieve the temperatures of the interior of the sun.
b. there is not enough hydrogen.
c. the helium shortage is driving up prices.
d. all the hydrogen is locked up in water already.