Please anser question in regaurds to programming language prolog:Which of the following queries has different behavior from the others?

$x=2,\frac{x}{\frac{?}{?}}=1$

$\frac{x}{\frac{?}{?}}=1,x=2$

$x=2,$dif$(x,1)$

dif$(x,1),x=2.$

All four have different behavior

All four have the same behavior