Offshore oil-drilling operations and Tankers

umeshpatil wrote:Offshore oil-drilling operations entail an unavoidable risk of an oil spill, but importing oil on tankers presently entails an even greater such risk per barrel of oil. Therefore, if we are to reduce the risk of an oil spill without curtailing our user oil, we must invest more in offshore operations and import less oil on tankers. <-- This is the conclusion. It states that we must invest more in offshore drilling because it causes less oil spills. So, to weaken this, we must make the risk of an oil spill from takers less likely. If tankers are safer, then the argument cannot hold.

Which of the following, if true, most seriously weakens the argument above?

a. Tankers can easily be redesigned so that their use entails less risk of an oil spill. This is the correct answer. If this were true, then the argument could not hold for reasons I stated above.
b. Oil spills caused by tankers have generally been more serious than those caused by offshore operations. This strengthens the argument. This is incorrect.
c. The impact of offshore operations on the environment can be controlled by careful management this strengthens the argument
d. Offshore operations usually damage the ocean floor, but tankers rarely cause such damage. This answer kind of weakens the argument. However, the argument states that "if we are to reduce the risk from an OIL SPILL"...This answer is here to confuse us. We think it weakens the argument. But, we are talking about oil spills, not overall environmental damage. This answer is incorrect.
e. Importing oil on tankers is currently less expensive than drilling for it offshore. This is irreverent to the argument. This answer is incorrect.

umeshpatil wrote:My analysis of this question:
Conclusion: Invest more in offshore operation AND invest less in oil on tankers.
Premise: 1. Offshore operation has UNAVOIDABLE risk of oil spill
2. Importing oil on tankers entails greater risk per barrel of oil.
So, Real weakener would one that weakens the conclusion. but, I am confused between many choices.

umeshpatil wrote:Offshore oil-drilling operations entail an unavoidable risk of an oil spill, but importing oil on tankers presently entails an even greater such risk per barrel of oil. Therefore, if we are to reduce the risk of an oil spill without curtailing our user oil, we must invest more in offshore operations and import less oil on tankers.
Which of the following, if true, most seriously weakens the argument above?
a. Tankers can easily be redesigned so that their use entails less risk of an oil spill.
b. Oil spills caused by tankers have generally been more serious than those caused by offshore operations.
c. The impact of offshore operations on the environment can be controlled by careful management
d. Offshore operations usually damage the ocean floor, but tankers rarely cause such damage.
e. Importing oil on tankers is currently less expensive than drilling for it offshore.