Final answer:
The correct symbol to denote that Line XY is parallel to line WZ is 'XY ∥ WZ', using the parallel symbol '∥'.
Step-by-step explanation:
To write that Line XY is parallel to line WZ using only symbols, you use the parallel symbol '∥', which is a pair of vertical lines. The correct way to write it is 'XY ∥ WZ'. This symbol is universally recognized in geometry to represent that two lines are parallel to each other. No matter where the lines are located in the plane, as long as they are always the same distance apart and never meet, they are considered parallel.