ANSWER
[tex]AA\text{'}=BB\text{'}[/tex]EXPLANATION
We have that line AB is translated in a plane to form line A'B'.
When a line/figure is translated, its shape and size do not change, which means that the distance between corresponding points on the pre-image and image must remain the same.
In other words, the distance between A and A' must be equal to the distance between B and B'.
Therefore, the correct answer is:
[tex]AA\text{'}=BB\text{'}[/tex]