All vectors are in Rn. Check the true statements below: A. Not every orthogonal set in Rn is a linearly independent set. B. An orthogonal matrix is invertible. C. If the columns of an m×n matrix are orthonormal, then the linear mapping x?Ax preserves lengths. D. If a set S={u1,...,up} has the property that ui?uj=0 whenever i?j, then S is an orthonormal set. E. The orthogonal projection of y onto v is the same as the orthogonal projection of y onto cv whenever c?0.