A number raised to a fraction would be the same as a root to the inverse of the fraction.
What that means is the sqrt(8) raised to 1/4 is the same as being 4th root of 8.
So rewriting the given equation you would have cubic root 8 x 4th root 8
Combine the roots by multiplying: 3 x 4 = 12
The equivalent equation would be C. 12 root 8 ^ x