If any determination shows the percentage of inflammable gas to exceed . . . . . . . ., determinate shall be made or samples of air taken at intervals not exceeding . . . . . . . . hours. for so long as such content exceeds that percentage and for the seven next following days.

A. 0.8, 24

B. 0.6, 14

C. 0.3, 8

D. 0.7, 20

Answer: Option A