Nearly 5 million children in the United States have asthma, the most

IMO - C

Nearly 5 million children in the United States have asthma, the most common chronic illness of childhood. In the state of Arizona, one in twenty children has asthma, whereas in New York, one in ten children has asthma. If a couple from New York should begin their family in Arizona, their children would be less likely to develop asthma than if the family should remain in New York.

Which of the following, if true, would most seriously weaken the conclusion drawn in the passage?

(A) Many asthmatics do not believe that moving to Arizona will significantly decrease the risk of developing asthma. - we are not concern with the believe of asthmatics - the facts stated in the argument are taken to be true - the authors conclusion is not in line with asthmatics believe - Out of scope
(B) The governor of New York's claims that statistics for her state are inaccurate has been proven false. - Actually strengthening the conclusion
(C) Whether or not a child develops asthma depends on genetic factors. - correct, stating that if Genetic factors are involved then a couple moving to A from NY does not guarantee that their child will be immune to asthma
(D) Developing asthma is usually a result of environmental factors - Actually strengthening the conclusion though we dont have any information that environment in A is better than in NY
(E) The average child from New York has better lung capacity than the average child from Arizona. - out of scope

Official Explanation

This is a Weaken question, as indicated by the language, "would most seriously weaken." The stimulus states that, since 1 in 20 children in Arizona has asthma and 1 in 10 children in New York has asthma, if New Yorkers move to Arizona to have children, their children will have less of a chance of developing asthma.

The assumption is that it is the location itself that explains the difference between the statistics, and not some other factor. A weakener will attack the author's assumption. It will make it less likely that the location is what is causing the different rates of asthma. The correct choice might do this by either addressing something about the locations themselves, or by suggesting some other reason for the different asthma rates.

(C) suggests another reason for the different asthma rates, and is therefore correct. If genetic factors are responsible for asthma, then environment (i.e., state of birth) has no role.

(A) is incorrect because whether asthmatics believe that moving to Arizona will decrease the risk of developing asthma has no bearing on whether moving to Arizona actually will decrease such risk.

(B) just confirms that the statistics are accurate. This was never in question, however. The evidence should always be accepted as true. The question is whether the conclusion follows from that evidence. (B) doesn't deal with this.

(D) is a 180, as it would strengthen the argument if true. The argument assumes that the locations (i.e., environment) are what explain the different asthma rates. (D) lends support to that assumption.

(E) deals with lung capacity, not asthma. The argument is about asthma, and (E) states nothing to connect asthma to lung capacity. Thus, (E) is irrelevant to the argument.

TAKEAWAY: With Weaken questions, keep the focus on the connection between the stated evidence and the conclusion - the assumption. Don't forget that the task is to attack that connection. That will make it easier to avoid wrong choices.