If the coefficient of `x^7in[a x^2-(1/(b x^2))]^(11)` equal the coefficient of `x^(-7)` in satisfy the `[a x-(1/(b x^2))]^(11),t h e naa n db` satisfy the relation `a+b=1` b. `a-b=1` c. `b=1` d. `a/b=1`