Critical Reasoning

In the past the country of Siduria has relied heavily on imported oil. Siduria recently implemented a program to convert heating systems from oil to natural gas. Siduria already produces more natural gas each year than it burns, and oil production in Sidurian oil fields is increasing at a steady pace. If these trends in fuel production and usage continue, therefore, Sidurian reliance on foreign sources for fuel should decline soon.

Which of the following is an assumption on which the argument depends?

A. In Siduria the rate of fuel consumption is rising no more quickly than the rate of fuel production.
B. Domestic production of natural gas is rising faster than is domestic production of oil in Siduria.
C. No fuel other than natural gas is expected to be used as a replacement for oil in Siduria.
D. Buildings cannot be heated by solar energy rather than by oil or natural gas.
E. All new homes that are being built will have natural-gas-burning heating systems.

OA: A

can someone explain this and how to choose this kind of Assumption question?

thank u so much!

IMO A

Treat this question as any other assumption question. Try to find a missing link between the evidence and the conclusion.

Conclusion: Sidurian reliance on foreign sources for fuel should decline soon.
Evidence: Oil production is increasing and natural gas' production is anyway more than what Sidurian consume.

Missing link or prephrase: The production might have been more than the consumption of oil. Then only we can say that Sidurian reliance on foreign sources for fuel should decline soon.

Now check out the answer choices. Only A says this (though in a different way, GMAT style). To confirm, negate it and see if conclusion fails or not. Lets see.

Negate: 'In Siduria the rate of fuel consumption IS rising more quickly than the rate of fuel production.' -> If consumption is rising more quickly then production, then Siduria will definitely need more oil and hence then reliance on foreign sources should NOT decline.

See how the conclusion falls apart when we negated choice A.

Therefore, A.
Thanks.