The nullspace of a matrix aa is the solution space of the homogeneous system ax=0ax=0. b. a linear system is solvable if and only if the vector of constants belongs to the column space of the coefficient matrix of the system. c. a subspace of a vector space vv cannot contain only a finite number of elements. d. the span of the columns of a matrix is called the column space of the matrix. e. a nonempty subset ww of some vector space vv is called a subspace of vv if ww is closed under linear combinations. f. the set of all vectors of the form [1,x, y]t[1,x, y]t, where xx and yy range over all real numbers, is a subspace of r3r3. g. the set of all vectors of the form [0,x, y]t[0,x, y]t, where xx and yy range over all real numbers, is a subspace of r3r3. h. none of the above