Determine whether the following matrices are in reduced echelon form. If a matrix is not in reduced echelon form, give a reason. (a) 1 0 2 0 1 3 Yes. No. There is at least one row consisting entirely of zeros that is not grouped at the bottom of the matrix. No. The first nonzero element of at least one row is not 1. No. There are some non-zero elements in at least one column that contains a leading 1. No. The leading 1 of at least one row after the first is not positioned to the right of the leading 1 of the previous row.