What economic policy did opec use which led to the energy crisis? a. tariff b. quota c. subsidy d. embargo

"For a time, geopolitical events and natural disasters had strong short-term effects on oil prices, such as North Korean missile tests, the 2006 conflict between Israel and Lebanon, worries over Iranian nuclear plans in 2006, Hurricane Katrina, and various other factors. By 2008, such pressures appeared to have an insignificant impact on oil prices given the onset of the global recession. The recession caused demand for energy to shrink in late 2008, with oil prices collapsing from the July 2008 high of $147 to a December 2008 low of $32. Oil prices stabilized by August 2009 and generally remained in a broad trading range between $70 and $120 through November 2014, before returning to 2003 pre-crisis levels by early 2016."

The used coins.. .