If a person covers the same distance by walking, by cycling and by running with speeds in the ratio 1 ∶ 9 ∶ 3 respectively, then the ratio of the ratios of their times and speeds of the three modes of travel is
1
1 ∶ 1 ∶ 1
2
1 ∶ 81 ∶ 9
3
81 ∶ 1 ∶ 9
4
1 ∶ 9 ∶ 81