Which of the statements below implies that a linear system Ax=b is consistent? A. The rightmost column of the augmented matrix is a pivot column. B. An echelon form of the augmented matrix has a row whose all entries are zero except for the right-most entry. B. An echelon form of the augmented matrix has a row whose all entries are zero except for the right-most entry. C. The rank of the augmented matrix is larger than the rank of the coefficient matrix. D. There are free variables in the system. E. All pivot positions of the augmented matrix [A b] are located in the coefficient matrix.