The editorial concludes that "international law" is not effective law.
Why? Because the power fo the police to enforce a society's laws makes those laws effective and there is no international police force.
Answer choice (B) is incorrect because it overlooks the possibility that there is another way to make international law effective.
Note that the editorial does not say that police are the only effective enforcement mechanism. It is entirely possible that fines could work just as effectively as police forces in backing up laws.
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