Which equation finds the volume of a cube with a side length of 2n^6 units?
a.(2n^6)^3=8n^18 cubic units
b. (2n^6)^3=2n^18 cubic units
c. 2(n^6)^3=2n^18 cubic units
d. 2(n^6)^3=6n^18 cubic units
