Answer:
Water is the correct answer.
Step-by-step explanation:
The whole process of extraction of oil from oil shales involves water in so many ways, from extraction to processing to selling the oil. Just in the United States, it is necessary to use from 4 to 8 billion of cubic meters everyday for oil refining, almost two times compared with what American household user in the same period of time. Due to this, b is the correct answer.