question from OG10, why A is wrong

duongthang wrote:Pls, explain, why A is wrong, OA will be posted latter.

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?

In a resolve the paradox questions, the correct answer choice should actively resolve both sides of the paradox. It should allow both sides to be factually correct. Because we are not seeking to disprove one side of the situation we must select the answer choice that contains a 'possible cause' of the situation. So, when examining answers, ask yourself if the answer choice could lead to the situation in the stimulus. If yes, the answer choice is correct.

(A) The cost of oil has fallen dramatically.
Incorrect : This addresses only one side of the paradox. 'Dramatic fall in the cost of oil' by itself will not make 'New Solar Power plants' more economical than 'New Oil-Fired plants'

(B) The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.
Incorrect : Once again this answer choice addresses only one side of the paradox and does not explain 'a possible cause' of the situation.

(C) Technological changes have increased the efficiency of oil-fired power plants.
Correct : In the stimulus it is implied that 'technological changes have increased efficiency of 'solar power plants'.... This answer choice says 'technological changes have increased the efficiency of 'oil fired power plants'... Thus, it allows both sides to be factually correct and also explains a possible cause of the situation.

(D) Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.
Incorrect : Coal-fired or nuclear power plants does not help the discrepancy between 'solar power plants' and 'oil fired plants' Eliminated.

(E) When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.
Incorrect : The question asks about 'economic viability of solar power plants' not 'economic viability of exploiting reserves of oil'. Eliminated.

kstv wrote: (C) Technology is also making oil based plants efficient. So the power generated from $ 35 is more now than before. Possible that efficiency is being matched and this expalins the constant.

IMO C.[/spoiler]