Answer:
C. 384 mm2
Explanation:
In order to find ONE side, you would multiply 8x8 (in this scenario at least).
You would then get this:
8mm x 8mm = 64mm2
But we're not done yet!
In order to find all six sides, you need to multiply the last number/area by six
You would then get:
64 x 6 sides = 384mm2
Hope this helps!