Hi vikky,
The theory of negation (or, as we call it, the negation test), hinges on the role of assumptions. Assumptions are the information that is
necessary for an argument to hold. That means, if you negate the correct assumption, the argument must
not hold!
So, here is a simple "Chemical X should be restricted because all poisons should be restricted" is a simple example. Suppose we are wondering if an answer choice, "Chemical X is a poison," is the correct assumption. Well, what if it's false? What if Chemical X is
not a poison? Well, the argument falls apart! That means we have the right answer.
The thing about the Negation test is, it's not very efficient. If you find that you're consistently down to two answer choices, it can be a great tie breaker. But if you're practicing with Kaplan strategies, you shouldn't need it! Focus on predicting what the answer should be, and looking for the best match!