Answer:B
Step-by-step explanation:
if you look at the two row echlon form you can see that it has leading entries(starting form left) that all one and there are no-zero elements above diagonal which can be any numbers (2,3,4, 6, x,y,x).
However reduced row echelon of has always leading elements 1 and are on diognal, this form is always like this therefore we can infer that reduced row echlon form is always uniqe as oppose to row echelon form.