Advertisement: Clark brand-name parts are made for cars manufactured in this country. They satisfy all of our governm...

Ravi July 19, 2019

@Julie-V,

Happy to help. Let's take a look at (A), (C), (D), and (E).

This is a strengthen with a necessary premise question. We can use the
negation test to see which answer is correct. If the negation of the
answer choice makes the argument fall apart, then that answer choice
is the correct answer.

(A) says, "Clark parts are available only in this country"

The negation is, "Clark parts are available in places other than this country"

It is necessary that Clark parts are available in this country, but it
is not necessary that they're available only in this country. The
negation doesn't make the argument fall apart, so (A) isn't the
correct answer choice.

(C) says, "no foreign-made parts satisfy our government standards"

The negation is, "at least some foreign-made parts satisfy our
government standards"

If (C) is true, it could strengthen the argument for buying Clark
parts over foreign-made parts, but it's not necessary for one to do
so. The negation of (C) doesn't wreck the argument, so we know (C)
isn't the right answer choice.

(D) says, "parts that satisfy our government standards are not as
poorly constructed as cheap foreign-made parts"

(D)'s negation is, "parts that satisfy our government standards are as
poorly constructed as cheap foreign-made parts"

(D)'s negation makes the argument fall apart. If the Clark parts are
cheaply made, then the big piece of evidence against the foreign-made
ones is removed, making the argument fall apart. Thus, (D) is the
correct answer choice.

(E) says, "if parts are made for cars manufactured in our country,
they are not poorly constructed"

(E)'s negation is, "parts can be made for cars manufactured in our
country and be poorly constructed"

If (E) were true, it'd mean that Clark parts aren't poorly
constructed. This would guarantee the conclusion of the argument since
we know that the foreign-made parts might be poorly constructed.
However, there may be other parts made for domestic cars other than
Clark parts, so this is not necessary. Thus, (E)'s negation doesn't
make the argument fall apart, so we can get rid of this choice.

Does this make sense? Let us know if you have any more questions!