The word “shrink”, in line 3, could be better substituted by which ...

READ THE TEXT AND ANSWER QUESTIONS 41 TO 46.

TEXT

Petroleum Alternatives. A new promising source

Human consumption of fossil fuels is expected to fully deplete the Earth’s crude oil reserves by the year 2060. As underground reservoirs of oil continue to shrink, we have no choice but to find alternatives. One promising source, with much cleaner emissions, is called bio-diesel. Bio-diesel is often made from soybean oil, although it can be made from any vegetable oil that is not elementally different from soy. Bio-diesel can even be made from used cooking oils that homes or restaurants would otherwise dispose of. Biodiesel can be used without constraint in any vehicle that runs on diesel—no modifications are needed. Presently, diesel engines can take up to 20 percent soy in their soy-diesel blend. As the need for bio-diesel increases and the technology improves, we may soon witness the extinction of the fossil-fueled vehicle.This is good news for the planet, as biodiesel is a more stable source of energy than petroleum, and it reduces contamination of our air and water.