First choose which of the following statements are correct. If there is more than one reason why the system is not in echelon fo
rm, type the letters as a comma separated list. If the system is in echelon form, make sure to type D as your answer. A. The system is not in echelon form because a variable is the leading variable of two or more equations. B. The system is not in echelon form because the system is not organized in a descending "stair step" pattern so that the index of the leading variables increases from the top to bottom. C. The system is not in echelon form because not every equation has a leading variable. D. The system is in echelon form.