Answer
(b) 8
Work Step by Step
Let $x$ be the length of each edge of the cube. Then the volume of the cube is $V_1 = x^3$.
When the length of each edge is doubled, each edge of the cube has a length of $2x$. The volume of the new cube is $V_2 = (2x)^3 = 8x^3 = 8V_1$
The correct answer is (b) 8