Complete the pattern:

The given figure is symmetrical about its central vertical axis. This is evident from the upper half, where the figure in the top-right quadrant is the mirror image of the figure in the top-left quadrant.

Applying the same principle to the lower half, the figure in the bottom-right quadrant must be the mirror image of the figure in the bottom-left quadrant.

The bottom-left quadrant contains a diagonal extending from its upper-left corner to its lower-right corner, together with a short line segment connecting this diagonal to the adjacent side. When this figure is reflected about the vertical axis, the diagonal extends from the upper-right corner to the lower-left corner, and the short line segment connects the diagonal to the left side of the quadrant.

Among the given options, only Option 4 satisfies this condition. In Options 1, 2 and 3, the lines meet at a point within the square rather than forming a continuous corner-to-corner diagonal, and therefore they do not complete the pattern.

Hence, Option 4 is the correct answer.