Southwest Regional Drager BG4 Exam Taken from the 2019 Southwest Regional Mine Rescue Contest held in Ruidoso, New Mexico Progress Indicator: Question 2 of 30 2.  Methane is most explosive at what range? Choices: 5% to 15% with at least 12.1% oxygen 9.5% to 12.5% with at least 12.1% oxygen 5% to 10% 9.5% to 10%