In the Mediterranean Sea, Mercury levels in the water and in fish are generally three times as high as in the Atlantic Ocean. Mercury in sea water can come from natural sources. However, the Mediterranean is a virtually enclosed sea, and year after year for the past few decades, large amounts of mercury have been discharged into it by industries. So, industrial pollution is probably the prime cause of Mediterranean’s exceptionally high mercury levels.
Which of the following, if true, most seriously weakens the conclusion?
A The Atlantic coastline of Europe is, on the whole, even more heavily industrialized than Europe’s Mediterranean coastline.
B Museum specimens of fish caught in the Mediterranean nearly a century ago have been found to have mercury levels only a little lower than those of fish caught there today.
C The mercury level in the Mediterranean is not as high as that in certain parts of the Atlantic that are immediately offshore from sources of industrial pollutions.
D Most of the industrial pollution that is charged into Mediterranean reaches the sea by way of rivers, with only a small part discharge directly into the sea by industries on the coastline.
E Some of the mercury contained in seawater worldwide comes from atmospheric pollution that is precipitated into the water.
The material traditionally used for make kettles in which water for teas is boiled is iron. When water is brought to a boil in these tea kettles, minute traces of iron dissolve in the water. These trace amounts of iron affect the taste of the tea. The use of tea kettles made of nontraditional materials that do not dissolve in water would therefore generally improve the taste of the tea.
Which of the following is an assumption on which the argument depends?
A Some metals do not dissolve in boiling water.
B Iron from kettles is the only impunity that is found frequently in water used for tea.
C Trace amount of dissolved iron do not improve the taste of tea.
D A significant number of people would be willing to switch from iron tea kettles to tea kettles made of nontraditional materials.
E Tea can be made without bringing the water to a boil.