Critical Reasoning

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.

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.

In my opinion the correct answer should be A. Here's why:

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.

I hope this helps. Please ask if you have other questions

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.

You're thinking about this all wrong. The conclusion is that the only way to reduce oil spills and still maintain normal oil supplies is by investing more in offsfore operations and importing less.

All we need to do to weaken this is find a way that importing can be done in a way that makes spills less likely. As Alex above points out, A does this perfectly. If we can redesign tankers such that the problem of spilling no longer exists, then we've clearly weakened the conclusion that off-shore drilling is our only option. Answer is A

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.

Mitch and Marty could you guys please help me on this one.

Here is my take.

Conclusion: Invest in offshore rather than in Tankers
Premise: Currently, Tankers entail greater risk than offshore drilling.

We need to weaken. So we need to show that Tankers is safer than Offshore. I was able to narrow down to
A and D. I selected A because of the language. In the premise 'currently' is used but in A, the answer is saying in the future tankers are safer. But D looks good too. If I read carefully, D weakens the premise(the first sentence), but the premise is a fact and we cannot weaken it.

Could you guys explain how we could eliminate D. In stressful situations, I would have selected D.

Thanks in advance,
Al