Answer:
3, 4, 6
Step-by-step explanation:
Only these dimensions will give you the areas of each face, the other dimensions will not.
3, 4, 6:
3 x 4 = 12
3 x 6 = 18
4 x 6 = 24
12, 18, 24:
12 x 18 = 216
None of the faces has 216 as its area
3, 4, 8:
4 x 8 = 32
None of the faces has 32 as its area
2, 9, 12:
9 x 12 = 108
None of the faces has 108 as its area