Colorless diamonds can command high prices as gemstones. A type of less valuable diamonds can be treated to remove all color. Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones. However, only 2 percent of diamonds mined are of the colored type that can be successfully treated, and many of those are of insufficient quality to make the treatment worthwhile. Surely, therefore, the vast majority of colorless diamonds sold by jewelers are naturally colorless.
A serious flaw in the reasoning of the argument is that
In Country X's last election, the Reform Party beat its main opponent, the Conservative Party, although pollsters, employing in-person interviews shortly before the vote, had projected a Conservative Party victory. Afterwards, the pollsters determined that, unlike Conservative Party supporters, Reform Party supporters were less likely to express their party preference during in-person interviews than they were during telephone interviews. Therefore, using only telephone interviews instead would likely result in more accurate projections for the next election.
Which of the following statements, if true, would most support the argument in the passage?
Height-for-age standards
The World Health Organization (WHO) has produced a comprehensive set of growth standards for children. These standards are based on studies of children living in 6 nations on 5 continents under optimal conditions with respect to health and nutrition. The table displays the percentile distribution of height, in centimeters, at 3-month intervals, for boys ages 2 through 5 according to the WHO model. In a model population—a large population of boys ages 2 through 5 that conforms to the WHO growth standards—for n = 3.15, 50. 85. and 97, the nth percentile in height for a given age is the unique height among boys of that age that is greater than or equal to n percent, and less than or equal to (100 - n) percent, of heights of boys of that age.

Weight-for-height standards
The graph shows the percentile distribution of weight, in kilograms, for heights from 80 cm to 120 cm. for boys ages 2 through 5, according to the WHO model. In a model population, for n = 3,15,50,85, and 97. the nth percentile in weight for a given height is the unique weight among boys of that height that is greater than or equal to n percent, and less than or equal to (100 - n) percent, of weights of boys of that age.
