Answer:
a)If political factors make petroleum expensive or impossible to obtain, the use of shale oil might increase.
Step-by-step explanation:
The importance of shel oil is that it is widely abundant in the US, the main problem is that to this day it is still too expensive, or at least more expensinve than oil, and it has a lot of enviromental hazards, so the positive does not outweights the negative, the only way in which production would increase is if political problems made petroleum expensive.