The correct option is A 160
The side of each cube = 3√64 = 4 cm.
Also, surface area of a cuboid = 2((l×b)+(b×h)+(l×h))
Here, l = 8 cm, b = h = 4 cm
So, surface area of cuboid = 2((8×4)+(4×4)+(8×4))
= 2(32 + 16 + 32)
= 160 cm2
Also, after joining two cubes, the surface area of resulting cuboid is 10a2, where 'a' is the side of original cube.