Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade. However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.

Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?

(A) The cost of oil has fallen dramatically.

(B) The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.

(C) Technological changes have increased the efficiency of oil-fired power plants.

(D) Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.

(E) When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.

Given that the contribution of fossil fuels constitutes the majority of the current energy mix, and taking into account the growing demand for energy and carbon intensity, we are at a crossroads: designing a new intelligent energy model. The energy challenge we face must have a global response, in which all available, conventional and alternative forms of energy coexist; all those forms of energy that can be produced in a balanced, safe way, with universal accessibility, competitive and respectful with the environment.

Much of what has served us in the past will not work in the future, with the great exception of innovation and technology as they will continue to be the fundamental keys to building a new energy model.