Which expression correctly states that xy is congruent to vw?

We are given to lines XY and VW. Now we need to determine the expression that correctly states that these lines are congruent. One possibility to prove that they're congruent is if they are two separate lines and:

XA is congruent to VB,
AY is congruent to BW
XA + AY = XY
VB + BW = VW

Then we can conclude that if the statements above are true, XY and VW must be congruent to each other. 

Another possibility is that they are two sides of an isosceles rectangle XYVW and are opposite sides of the rectangle.