求助－这道逻辑题不理解

From 1998 to 2008, the amount of oil exported from the nation of Dettlandia increased by nearly 20% as the world’s demand soared. Yet over the same period, Dettlandia lost over 8,000 jobs in oil drilling and refinement, representing a 25% increase in the nation’s unemployment rate.

Which of the following, if true, would best explain the discrepancy outlined above?

A- Because of a slumping local economy, Dettlandia also lost 5,000 service jobs and 7,500 manufacturing jobs.

B-Several other countries in the region reported similar percentages of jobs lost in the oil industry over the same period.

C- Because of Dettlandia’s overvalued currency, most of the nation’s crude oil is now being refined after it has been exported.

D- Technological advancements in oil drilling techniques have allowed for a greater percentage of the world’s oil to be obtained from underneath the ocean floor.

E-Many former oil employees have found more lucrative work in the Dettlandia’s burgeoning precious metals mining industry.