You will love the Kaplan
's OE. Its lengthy.
Takeaway : Non-causal argument can be destroyed by the assumption which establishes the causal relationship.
Reading the question stem first (always a fine idea)
for question 19 warns you to be on the alert for
something the author has overlooked. The author
argues against the notion that fertility treatments
are responsible for the increased incidence of twins
by presenting an alternative explanation—that the
increase has occurred because more women are
having children later in life, and these older women
are statistically more likely to bear twins. This
sounds plausible, but remember the key questions
in GMAT causal arguments: Can the causality be
reversed? Is coincidence confused for cause? Could
another cause have been at work? If women over 35
are much more likely to use fertility treatments that
often result in twin births, then it’s possible that the
twin births among older women are in fact due to
fertility treatments. The problem (E) points out is
not that the “alternative explanation” is illogical or
impossible, but that it might be dependent on the
very explanation it’s supposed to replace.
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