Explanation

Creating a filter: supposing that we don't find an error in the original sentence, we can set out to eliminate the other answer choices and come back to (A).

Finding objective defects: choice (B) is wrong in the use of "should be." That would be putting a moral burden on the dolphins for their state of existence. Or, it would mean that dolphins should be something they are not, quite contrary to the intended meaning, which is to say what dolphins are. Choice (B) is out. Choice (C) is out for the unnecessary use of "being." In choice (D), the phrase "as if" conveys a comparison with something that is contrary to fact, and in the intended meaning, there is not actually a comparison or a contrary-to-fact element. Choice (E) looks good, so we are left with (E) and (A). Choice (A) has "to be" at the beginning, and (E) uses the infinitive "to ban." (E) is better on both counts. The nation declared dolphins non-human persons; the words "to be" are superfluous. The correct answer is (E).