Although there has been great scientific debate for decades

[rahul.gmat]

Although there has been great scientific debate for decades over global warming, most scientists now agree that human activity is causing the Earth’s temperature to rise. Though predictions vary, many global warming experts believe that average global temperatures will rise between three and eight degrees Fahrenheit during the next century. Such an increase would cause an alarming rise in sea levels, displacing millions of people by destroying major population centers along the world’s coastlines.

Which of the following is an assumption in support of the argument’s conclusion?
A) New technological developments in the next century will not divert rising seas from the world’s coastal cities.
B) Individuals will not become more aware of the steps they can take to reduce the emission of greenhouse gases.
C) Rising sea levels similarly affect all coastal population centers.
D) Some global warming experts predict a greater than eight degree Fahrenheit increase in global temperatures during the next century.
E) Human activity is the sole cause of increasing global temperatures.
The argument concludes that rising sea levels caused by global warming will destroy major coastal population centers and displace millions of people. Any assumption in support of this conclusion would have to corroborate that these events will definitively take place.

(A) CORRECT. If new technological developments in the next century allow people to divert rising seas from the world’s cities (i.e., population centers), cities will not be destroyed and millions of people will not be displaced. Thus, a necessary assumption is that these technologies will not be developed.

(B) A simple awareness of the steps to reduce emissions in no way undermines the argument’s conclusion, as this answer choice does not describe any action being taken by individuals. Additionally, greenhouse gases are never mentioned as the primary by-product of human activity that causes global warming, and are therefore not sufficient to address the argument.

(C) The argument never suggests that all coastal population centers are similarly affected; this choice is too extreme and overreaching for the argument’s conclusion.

(D) This might be true, but it is not an assumption on which the conclusion rests. Instead, this answer choice is simply an inference that might be drawn from the premises.

(E) The idea that human activity is the sole cause of global warming is neither suggested nor assumed by the argument. In addition, the wording "sole cause" is too extreme.

Here (A) is as good as (B). The explanation says that (B) talks about awareness and not actions, it is clearly said "more aware of the steps they can take to reduce the emission of greenhouse gases" and also clearly indicated in the argument that human activity is the primary cause. This makes (B) as good as (A), in fact closer to the premises of the argument. Could you pls explain whyh (A) is better?

[StaceyKoprince]

As with passages, you cannot read anything more into an argument or answer choice than is explicitly presented to you.

Answer B simply says that they will become more aware of steps they can take. It does not say that they will take those steps. In the real world, people would say you were being too picky if you argued that it didn't explicitly say they would take the steps. On the GMAT, though, this is exactly what you do: you cannot connect the dots by assuming that they will take the steps simply because they are more aware of them. Well, you can if you want... but you won't get the right answer. :)

[JacobW468]

Negating the solutions here really help to see if the conclusion falls apart.

(a) New technological developments in the next century WILL divert rising seas from the world’s coastal cities. (clearly populations are saved)
(b) Individuals WILL become more aware of the steps they can take to reduce the emission of greenhouse gases. (out of scope)
(c) Rising sea levels affect all coastal population centers DIFFERENTLY. (statement doesn't say anything about ALL coastal centers)
(d) Some global warming experts predict a LESS than eight degree Fahrenheit increase in global temperatures during the next century. (Ok... doesn't help me here, 3-8 is already quoted)
(e) Human activity ISN'T the sole cause of increasing global temperatures. (Ok... still doesn't help those guys out in the beachfront apts)