From 1978 to 1988, beverage containers accounted for asteadily decreasing percentage of the total weight of household garbage in theUnited States. The increasinglywidespread practice of recycling aluminum and glass was responsible for most ofthis decline. However, although aluminumrecycling was more widely practiced in this period than glass recycling, it wasfound that the weight of glass bottles in household garbage declined by a greaterpercentage than the weight of aluminum cans.

　　Which of the following, if true of the United States inthe period 1978 to 1988, most helps to account for the finding?

　　(A) Glass bottles are significantly heavier than aluminumcans of comparable size.

　　(B) Recycled aluminum cans were almost all beveragecontainers, but a significant fraction of the recycled glass bottles hadcontained products other thanbeverages.

　　(C) Manufacturersreplaced many glass bottles, but few aluminum cans, with plastic containers.

　　(D) The total weight of glass bottles purchased byhouseholds increased at a slightly faster rate than the total weight ofaluminum cans.

　　(E) In many areas, glass bottles had to be sorted bycolor of the glass before being recycled, whereas aluminum cans required nosorting.

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