20. (3%) Which of the following statements is true?
(A) If none of the vectors in the set S = {v1, v2,v3} in R3 is a multiple of one of the other vectors, then S is
linearly independent.
(B) If A is a subspace, then its complement is also a subspace.
(C) If a square matrix A has independent columns, so does A2.
(D) Every vector space has at least two distinct subspaces.