Generally speaking, when dealing with assumption questions there are two key tests to bear in mind: The Why? test and the negation test. Neither method is superior to the other, rather it depends on the temperament of the student. Some students find one method helpful whereas others prefer the other method.

The first step is to determine the main point of the argument. In most cases, the main point is the logical conclusion of the argument. In this case, the question stem tells us that the main point is the explanation offered by the author. The explanation is contained in the very first sentence: This piece of pottery must surely date from the late Minoan period.

How do we find the main point? There is no sure fire way, but the main point generally has one or more of the following characteristics:

1. It is mentioned in the question stem (i.e., the plan will succeed).
2. It contains a modal verb such as must, should, or will.
3. It is accompanied by indicator words such as therefore, thus, clearly, or surely.
4. It is an opinion/claim rather than a fact.
5. It is supported by other portions of the argument.

Since the first statement is our leading candidate for the main point, we can ask ourselves whether other portions of the argument support it. This is where the Why? test comes in. Why does the author think that the pottery is from the late Minoan period? Because the women are bare breasted, there's a bull, and there is a black semi-gloss glaze to the pottery. The fact that there are reasons that support the initial claim is good reason to believe that it is the main point.

There are two types of reasons to support a main point. The first type are the stated reasons. These are usually called premises. The unstated reasons are usually called assumptions. Since we're looking for an assumption, the assumption should also answer the question Why? This is the reason for the Why? test.

For example, let us apply the Why? test to answer choice B. "This piece of pottery must surely date from the late Minoan period. Why? Because the bull is an animal that was important to most ancient cultures." Does this support the main point? Not really. If the bull is important to most ancient cultures, then seeing a bull on a piece of pottery hardly makes it certain that the pottery is from the late Minoan period.

Perhaps you continue employing the Why? test but you aren't totally convinced. Perhaps you find yourself torn between choice (A) and choice (E). Both of these choices seem to support the main point. How can you decide between them? If you find yourself in such a dilemma, you can always try the negation test. Let's try it now.

Let's assume that (A) is false. Black semigloss glazed pottery was not made only during the late Minoan period. In fact, it was made through several Minoan periods. Does this ruin the argument? Not really. The argument is that the pottery is late Minoan not only because of the black semigloss glaze but also because of the bull and the dress of the women.

(E), on the other hand, when negated, is fatal to the argument. If there are no key characteristics of works of art that can be shown to be typical of a particular period, then the author's argument fails. Accordingly, we can see why (E) is the credited response.