The percentage of inflammable gas in an u/g coal mine should not exceed

A. 0.75% in the general body of the return air of any ventilation district and 1.5% in any place of the mine

B. 0.75% in the general body of the return air of any ventilation district and 1.25% in any place of the mine

C. 0.5% in the general body of the return air of any ventilation district and 1.25% in any place of the mine.

D. 0.5% in the general body of the return air of any ventilation district and 1.5% in any place of the mine.

Answer: Option B