Which of the following expression(s) is/are equivalent to z (y x)^-? Explain.(: Exclusive oR and x^-: negation of x) 1. (x^-y + xy) z 2. (x y)^-z^- + (x y)z 3. (xy^- + x^-y)z + (x^-y + xy^-)z^- 4. (xy^-z + x^-yz + xyz^- + x^-y^-z^-) 5. (xy^-z + x^-yz + xyz^- + x^-y^-z^-) 6. (xyz + xy^-z^- + x^-yz^- + x^-y^-z^-)