15 . In 1985 a consumer agency concluded that Xylo brand bicycles are safer to ride than a

15 . In 1985 a consumer agency concluded that Xylo brand bicycles are safer to ride than are Zenon brand bicycles. The agency based the conclusion on the ratio of the number of rider injuries to the number of riding hours for each brand of bicycle from 1981 through 19Yet for identically designed bicycles manufactured since 1985, the number of rider injuries has been twice as great among riders of Xylos as among riders of Zenons. Therefore, the agencys conclusion would have been different for the period since 19Which of the following is an assumption that, if true, supports the claim that the agencys conclusion would have been different for the period since 1985？

A．For the period since 1985, the number of riding hours for Zenons totaled at least half the number of riding hours for Xylos.

B．Of all the bicycles ridden in the period since 1985, the percentage of Xylos ridden was twice the percentage of Zenons ridden.

C．Prior to 1985, Zenon owners were more likely than Xylo owners to report the injuries they sustained while riding their bicycles.

D．In 1985 the agency had miscalculated the ratio for Xylos, for Zenons, or for both.

E．Soon after the agency had issued its report, consumer demand for Xylos increased more rapidly than did consumer demand for Zenons.

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