The main measures to save energy are as follows

Vigorously developing new energy sources, making extensive use of solar energy and geothermal energy, and making extensive use of hydropower and wind energy are all measures to develop new energy sources;

Only adopting new technology and equipment and updating backward technology and equipment are the main measures to save energy;

So choose D.

Train of thought analysis: The key to solve this problem is to know that the main measures to save energy are to adopt new technology and equipment and update backward technology and equipment.

Test comments: To solve this problem, we should distinguish between energy saving and new energy development measures.