Environmentalist: An increased number of oil spills and the consequent damage to the environment indicate the need for stricter safety standards for the oil industry.
Conclusion
The government has to at least require oil companies to put double hulls on their tankers and to assume financial responsibility for accidents.
Intermediate Conclusion
The national government needs to regulate industry safety standards.
Evidence
There have been an increased number of oil spills and consequent damage to the environment, and the oil industry refuses to take action.
Evaluate
The author defines a Problem and then proposes what he thinks is a mandatory Solution.
Typically with this form, there are two main assumptions - the Solution works (it's feasible / it doesn't backfire / it would address the issue) - there isn't any other Solution that would work at least as well
Goal
Look for an answer stating something we'd have to assume for the author's Solution to actually help when it comes to decreasing oil spills / environmental damage, or look for an answer ruling out any other possible way of dealing with this problem besides national government intervention.