Simplifyx⁻²y⁻⁶/ z⁻⁴. Express your answer with positive exponents. Assume that all variables are nonzero.
(A) x²y⁶z⁴
(B) x²y⁻⁶z⁴
(C) x⁻²y⁻⁶/z⁻⁴
(D) x⁻²y⁶z⁴