Crude oil is perhaps the most useful and versatile raw material that has become available for exploitation. By the mid-1980s, worldwide production was 53.4 million barrels a day. The world's reserves of crude oil add up to about 700 billion barrels, over half of which are in the Middle East. It is likely that some additional discoveries will be made of new reserves in coming years, and new technologies will be developed for more efficient recovery from known resources. Many experts believe that the supply of crude oil will probably extend into the 21st century, but probably not much longer. Which of the following can the reader infer from the passage above?
A.
New energy sources will be necessary in the future.
B.
You can become rich by discovering oil.
C.
Burning crude oil causes pollution.
D.
The price of oil fluctuates wildly and is totally unpredictable.