Working over the real numbers, expressions B and D are (almost) equivalent.
[tex] \dfrac{1}{x^{-1}} = \dfrac{1}{1/x} = x [/tex]
[tex] x^{\frac 1 3}x^{\frac 1 3}x^{\frac 1 3} = x^{\frac 1 3 + \frac 1 3 + \frac 1 3 } = x[/tex]
They're not quite equivalent when x=0 as the first is undefined, but we'll let that go because we can't argue with the online system.
Answer: B and D
