Which construction is illustrated above?

The given construction is illustrating parallel lines.

Step-by-step explanation:

In the given figure ,

1) Let it be Δ ABC with base BC.

2) Mark point D on side AB.  

3) Taking B as  point to draw an angle and with same measurement draw an arc  at point D.

4) Extend D to join AC at point E such that ∠ ADE = ∠ABC

these are corresponding angles .

Therefore,  DE ║ BC

We obtained a line DE parallel to BC.

Thus, the given construction is illustrating parallel lines.