Critical Reasoning

Flavonoids are a common component of almost all
plants, but a specific variety of flavonoid in apples
has been found to be an antioxidant. Antioxidants
are known to be a factor in the prevention of heart
disease.
Which one of the following can be properly inferred
from the passage?
(A) A diet composed largely of fruits and
vegetables will help to prevent heart disease.
(B) Flavonoids are essential to preventing heart
disease.
(C) Eating at least one apple each day will prevent
heart disease.
(D) At least one type of flavonoid helps to prevent
heart disease.
(E) A diet deficient in antioxidants is a common
cause of heart disease.

talaangoshtari wrote:Flavonoids are a common component of almost all
plants, but a specific variety of flavonoid in apples
has been found to be an antioxidant. Antioxidants
are known to be a factor in the prevention of heart
disease.
Which one of the following can be properly inferred
from the passage?
(A) A diet composed largely of fruits and
vegetables will help to prevent heart disease.
(B) Flavonoids are essential to preventing heart
disease.
(C) Eating at least one apple each day will prevent
heart disease.
(D) At least one type of flavonoid helps to prevent
heart disease.
(E) A diet deficient in antioxidants is a common
cause of heart disease.

A specific variety of flavonoid in apples has been found to be an antioxidant.
At least one flavonoid --> antioxidant.

Antioxidants are known to be a factor in the prevention of heart disease.
Antioxidant --> prevents heart disease.

Linking the two statements together, we get:
At least one flavonoid --> antioxidant --> prevents heart disease.
At least one flavonoid --> prevents heart disease.
Thus, D must be true:
At least one type of flavonoid helps to prevent heart disease.

The correct answer is D.

Hi GMATGuruNY,

I thought "at least one" is out of scope, since the passage says "a specific variety" of flavonoid is antioxidant and maybe we don't know that there is more than one type. Is this a general rule that we can apply in other questions that "a specific" is equal to "at least one"?

talaangoshtari wrote:Flavonoids are a common component of almost all
plants, but a specific variety of flavonoid in apples
has been found to be an antioxidant. Antioxidants
are known to be a factor in the prevention of heart
disease.
Which one of the following can be properly inferred
from the passage?
(A) A diet composed largely of fruits and
vegetables will help to prevent heart disease.
(B) Flavonoids are essential to preventing heart
disease.
(C) Eating at least one apple each day will prevent
heart disease.
(D) At least one type of flavonoid helps to prevent
heart disease.
(E) A diet deficient in antioxidants is a common
cause of heart disease.

When the GMAT asks which can be "properly inferred", the correct choice will state something that MUST be true given what is said in the prompt. So here all of the answers choices but one can be eliminated because only one, and not the most obvious one by the way, must be true given what is said in the prompt.

A) While this may seem to be a reasonable inference, this is not really supported by what is said in the prompt. All the prompt says is that one type of flavonoid found in apples is an antioxidant. This can't be extended to all flavonoids, and it also cannot be further extended to an inference that a vegetable rich diet will prevent heart disease.

B) While certain flavonoids may be antioxidants and may help prevent heart disease there is no reason given for their being "essential to preventing heart disease."

C) While apples contain antioxidant flavonoids and antioxidants and known to prevent heart disease, there is not in the prompt a logical chain of reasoning that serves as a solid foundation for concluding that one can prevent heart disease by eating one apple a day. For all we know, for some reason one cannot use the flavonoids found in apples. Alternatively, one may need to eat more than one apple a day to prevent heart disease. So while one may be tempted to choose this answer, it is not something that MUST be true given what is said in the prompt.

D) This is the best. While I find it still to be a bit of a stretch, because nowhere in the prompt is this type of flavenoid directly connected to the prevention of heart disease, the prompt does say that one type of flavenoid is an antioxidant and that antioxidants prevent heart disease. Therefore it's reasonable to infer that a flavenoid that is an antioxidant prevents heart disease.

E) This answer could be tempting, but actually the passage does not say that lack of antioxidants causes heart disease, only that antioxidants can prevent heart disease.

So D is the best answer.

One key thing in getting CR, and RC, questions right is noticing what is actually said in the prompt or the passage. People often do not get them right because they act as if things are being said when in fact those things were not said.

In this example, one could conclude, for instance, that one can infer that one can prevent heart disease by eating vegetables or an apple a day, but a closer look reveals that the prompt said only that apples contain a certain flavenoid.

So be careful to stick to what's actually said rather than what might be being said.

talaangoshtari wrote:Hi GMATGuruNY,

I thought "at least one" is out of scope, since the passage says "a specific variety" of flavonoid is antioxidant and maybe we don't know that there is more than one type. Is this a general rule that we can apply in other questions that "a specific" is equal to "at least one"?

At least one means ONE OR MORE.
Since a specific variety of flavonoid is antioxidant, it must be true that ONE OR MORE flavonoids are antioxidant.