State whether the following values represent length, area or volume.

a) [[$ 6 $]] m[[$ ^3 $]] length area volume

b) [[$ 3 $]] cm[[$ ^2 $]] length area volume

c) [[$ 2\pi $]] cm length area volume

d) [[$ 21 $]] mm[[$ ^3 $]] length area volume

e) [[$ 0,\!15 $]] cm[[$ ^2 $]] length area volume

f) [[$ 2\;000 $]] mm[[$ ^3 $]] length area volume

g) [[$ 6\pi $]] dm[[$ ^2 $]] length area volume

h) [[$ 289 $]] m length area volume