Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.
The conclusion of the argument is properly drawn if which one of the following is assumed?
(A) The cost of producing electric power at traditional plants has increased over the past 20 years.
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.
(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.

I will go with Ans. C.

Conclusion:
Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

We need to support the conclusion by adding(assuming) the below ans C.
C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.

Can't wait to see OA.
Thanks,
MRD.

D for me...

Conclusion: "Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants." we have to show that photovoltaic is less expensive than tradition plant.

premises for the conclusion: 1, cost of photovoltiac has gone down; 2, cost of traditional plant has gone up. these two premises might be fact but they are not sufficient for comparing as we don't know the starting cost levels. For instance, maybe 20 years ago photovoltiac cost 100 and now they cost 10 and traitional cost 10 and now they cost 12. From this it is clear that traditional is still cheaper. for author's conclusion to hold we have to show that the price of photovoltiac was either same or was less than the traditional plant. Choice C does that for us...

D due to "deny" test

Very good question +1

(A) The cost of producing electric power at traditional plants has increased over the past 20 years. - paraphrasing of "whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased"

(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants. - irrelevant

(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants. - it requires "at the same cost efficiency". Maybe we can apply "the recent technological advances" but decrease costs only by 1%.

(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants. - 1/10 and 20 times give us ambiguity. But "deny" test works perfect here

(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease. - decrease by 1%? 200%?. insufficient.
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I think its C.

Reason: The stimulus suggests that photovoltic power is now cheaper because of technological advancements. Becasue of these advancements, its now cheaper to create power using photovoltic power generators. There is an inherent assumption that the technological advancments made, only apply to the photovoltic power generation and not to the traditional fossil fuel power generators.

My arguments against C:

(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.

[PP] - photovoltaic plants
[TP] - traditional plants

An Economic effect of the recent technological advances

For example, a blade at [PP] was made from gold ($100'000) and a blade at [TP] was made from copper ($1'000). Due to inventions we can use new nanomaterial for blades and reduce cost of the blade to 950$. For [PP] economic effect is 90% but for [TP] is only 5%.
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So Whats the actual answer?

I'm waiting

I am with D on this one. Conclusion is talking about cost, C does not mention cost at all.

OA is D.

I understand what D is trying to say, but the number doesn't add up.

Lets say cost of Photovoltaic Power Plants is 19x, and cost of Fossil Fuel Plants is 1x. After 20 years, Photovoltaic Power Plants is now 1.9x and Fossil Fuel Plants increased 10% to 1.1x. Photovoltaic Power Plants is still more expensive. It doesn't go well with the conclusion that it offers a cheaper alternative.

I say they should change the number around in D a little.

Yes, I clicked into this thread from the SC1000 software Walker wrote. Although I agree D is the better answer (the lesser of all evil), but I just don't think the number add up. I am wondering if people have any OE available. Thanks