单项选择题

Passage Six
Savages, published in the U.S., Canada and England last fall and soon to be released in Europe, is the story how Huaorani have fought to avoid the fate—to preserve their land and ancient culture from destruction by oil companies rushing to extract the black gold beneath the forest. As the reader quickly guesses in this compelling tale, it is not the Indians that Kane regards as savages.
Though he is obviously an environmentalist as well as journalist, Kane has written more than a save-the-rain-forest polemic. Rather, it is a sometimes comic adventure in which the author sets out to answer the question that has puzzled oil companies and ecologists alike: Who are these Huaorani In the course of finding out, Kane spent many days being soaked by the constant jungle rains and bitten by countless insects. He contracted a rash of fungal infections and during one expedition nearly starved to death. He grew inured to Huaorani food including smoked howler-monkey arm and the tribe’s version of chichi-manioc that has been chewed, spat into a bowl and left to ferment into an alcoholic drink.
For all the hardships Kane endured, he found the Huaorani a charming people who were by turns wily and naive, fierce and helpless. Once an extremely war-like people, they have fought off every effort to "civilize" them, beginning with incursions of the Incas. But modem opponents are craftier than any Inca warrior. They are the smooth-talking government officials and company executives who try to convince the Huaorani that oil can be sucked from under the tribal homeland without doing any damage. That assertion, Kane points out, is devastatingly refuted elsewhere in the Ecuadorian rain forest, where pipeline breaks and oil-waste dumps have wiped out hectare after hectare of trees and wildlife. "Colonists" from elsewhere in Ecuador follow the oilrigs in, take over Indian land and then destroy the forest.
Kane befriended half a dozen tribal leaders, and together they launched a protest campaign to prevent the Maxus Energy Corp. of Texas from building a new oil road through the heart of Huaorani territory—a cause that was taken up by environmental groups across Europe and the U.S. But with Ecuador deep in debt and dependent on oil revenues for more than half its foreign exchange, the government could not be pressured. At the time of Kane’s last postscript, in May 1995, oil drilling was proceeding apace, and most of the Huaorani leaders had gone over to the other side: they were on the petroleum companies’ payrolls. The Spanish priest’s prophesy is sadly coming true. It can be inferred that "black gold" means ______.