Question

which sentence describes an important downside of oil extraction from tar sands?
a. it can increase the frequency of earthquakes in the local area.
b. it disrupts a larger area and produces less oil than drilling.
c. it can be used with both surface and underground mines.
d. it can increase risk of worker injury or fatality from mineshaft collapse.

Explanation:

Tar - sand oil extraction is a more surface - intensive process. It requires the removal and processing of large amounts of sand, which disrupts a larger land area compared to traditional oil drilling. Also, the oil yield per unit of material processed in tar - sand extraction is relatively low compared to the more concentrated oil sources accessed by drilling.
Option A: There is no significant evidence that tar - sand oil extraction increases earthquake frequency.
Option C: This is a description of its applicability (a neutral or even positive aspect in terms of versatility), not a downside.
Option D: Mineshaft collapse is more associated with traditional underground mining (not specifically tar - sand oil extraction which is more about surface - level processing of sand).

Answer:

B. It disrupts a larger area and produces less oil than drilling.