Step 1: Understanding the movement.
The person starts from point A and moves straight towards the south direction for 200 meters. This movement creates a straight line in the north–south direction.
Step 2: Effect of the 180° turn.
After reaching the end point, the person takes a 180° turn and returns to point A along the same path. A 180° turn means moving in the exact opposite direction, i.e., north, along the same straight line.
Step 3: Identifying the design element.
The complete journey traces a straight line along the north–south axis. In design terminology, a line running from north to south is identified as a vertical line.
Step 4: Eliminating other options.
(A) A point: Incorrect, because movement creates a line, not just a single point.
(C) A horizontal line: Incorrect, as horizontal lines run east–west, not north–south.
(D) A diagonal line: Incorrect, because there is no angular movement involved.
Step 5: Conclusion.
The primary design element formed after completing the journey is a vertical line.