Describe the Characteristics of an Augmented Matrix in Diagonal or Reduced-Row

Describe the characteristics of an augmented matrix in diagonal or reduced-row echelon form.

A) The matrix has zeros on the main diagonal and ones below the main diagonal.
B) The matrix has ones on the main diagonal and zeros below the main diagonal.
C) The matrix has ones on the main diagonal and zeros above the main diagonal.
D) The matrix has ones on the main diagonal and zeros everywhere else.