(B) The unusually high salt consumption in certain areas of Africa represents a serious health problem.
(C) Because of their blood pressure levels， most White Africans have markedly decreased their salt consumption.
(D) Blood pressures are low among the Yoruba， who， throughout their history， have been situated far inland from sources of sea salt and far south of Saharan salt mines.
(E) No significant differences in salt metabolism have been found between those people who have had salt available throughout their history and those who have not.
4.Two decades after the Emerald River Dam was built， none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 de美国GREes to 6 de美国GREes， scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.
Which of the following statements， if true， would most strengthen the scientists' hypothesis?
(A) The native fish species were still able to reproduce only in side streams of the river below the dam where the annual temperature range remains approximately 50 de美国GREes.
(B) Before the dam was built， the Emerald River annually overflowed its banks， creating backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34 de美国GREes， whereas the lowest recorded temperature of the river after the dam was built has been 43 de美国GREes.
(D)Nonnative species of fish， introduced into the Emerald River after the dam was built， have begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in North America.
5. An advertisement designed to convince readers of the 美国GREat durability of automobiles manufactured by the Deluxe Motor Car Company cites as evidence the fact that over half of all automobiles built by the company since 1970 are still on the road today， compared to no more than a third for any other manufacturer.
Which of the following， if true， most strongly supports the advertisement's argument?
(A) After taking inflation into account， a new Deluxe automobile costs only slightly more than a new model did in 1970.
(B) The number of automobiles built by Deluxe each year has not increased sharply since 1970.
(C) Owners of Deluxe automobiles typically keep their cars well maintained.
(D) Since 1970， Deluxe has made fewer changes in the automobiles it manufactures than other car companies have made in their automobiles.
(E) Deluxe automobiles have been selling at relatively stable prices in recent years.