题目内容：
请根据短文内容，回答题。Energy and Public Lands
The United States boasts substantial energy resources. Federal lands provide a good deal of US energy production, the US Department of the Interior manages federal energy leasing (租凭)both on land and on the offshore Outer Continental Shelf Production from these sources amounts to nearly 30 percent of total annual US energy production.
In 2000,32 percent of US oil,35 percent of natural gas, and 37 percent of coal were produced from federal lands, representing 20,000 producing oil and gas leases and 135 producing coal leases.
Federal lands are also estimated to contain approximately 68 percent of all undiscovered US oil reserves and 74 percent of undiscovered natural gas.
Revenues from federal oil, gas, and coal leasing provide significant returns to US taxpayers as well as State Government. In 1999, for example, $553 million in oil and gas revenues were paid to the US Treasury, and non-India coal leases accounted for over $304 million in revenues, of which 50 percent were paid to State governments. Public lands also play a critical role in energy delivery.
Each year, federal land managers authorize rights of way for transmission lines, rail systems, pipelines, and other facilities related to energy production and use.
Alternative energy production from federal lands falls behind conventional energy production, though the amount is still significant. For example, federal geothermal (地热) resources produce about 7.5 billion kilowatt-hours (千瓦时) of electricity per year,47 percent of all electricity generated from US geothermal energy. There are 2,960 wind turbines on public lands in California alone, producing electricity for about 300,000 people. Federal hydropower facilities produce about 17 percent of all hydropower produced in the United States.
Because of the growing US thirst for energy and increasing public unease with influence on foreign off sources, pressure on public lands to meet US energy demand is becoming more intense.
Public lands are available for energy development only after they have been evaluated through the land use planning process. If development of energy resources conflicts with management or use of other resources, development restrictions or impact moderation measures may be enforced, or mineral be banned altogether.
What is the main idea of this passage? A．Public lands are one of the main sources of revenues.
B．Public lands play an important role in energy production.
C．Public lands should be developed to ease energy shortage.
D．Public lands store huge energy resources for further development.
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