Determine whether the function (or mapping) is a linear transformation. (a) T:Mnn → R, where T(A) = tr(A). (b) T: Mon + Mun, where T(A) = -A. (c) T:Mmn → Mom, where T(A) = A^T. (d) T: Mnn → Mon, where T(A) = A- for all invertible matrices A of order n.