3. Mud from a lake on an uninhabited wooded island in northern Lake Superior contains toxic chemicals， including toxaphene， a banned pesticide for cotton that previously was manufactured and used， not in nearby regions of Canada or the northern United States， but in the southern United States. No dumping has occurred on the island. The island lake is sufficiently elevated that water from Lake Superior does not reach it.

　　The statements above， if true， most strongly support which of the following hypotheses？

　　（A） The waters of the island lake are more severely polluted than those of Lake Superior.

　　（B） The toxaphene was carried to the island in the atmosphere by winds.

　　（C） Banning chemicals such as toxaphene does not aid the natural environment

　　4.To prevent some conflicts of interest， Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluded， however， that such a prohibition would be unfortunate because it would prevent high-level government officials from earning a livelihood for three years.

　　The official's conclusion logically depends on which of the following assumptions？

　　（A） Laws should not restrict the behavior of former government officials.

　　（B） Lobbyists are typically people who have previously been high-level government officials.

　　（C） Low-level government officials do not often become lobbyists when they leave government service.

　　（D） High-level government officials who leave government service are capable of earning a livelihood only as lobbyists. （E） High-level government officials who leave government service are currently permitted to act as lobbyists for only three years.