Step 1: Read the line directions at the four sides of the hole.
Across the hole’s edges, one heavy diagonal line approaches from the bottom and must continue through the missing square. Two other fine lines enter from the left–top region and exit toward the right–top.
Step 2: Match edge continuity with options.
We need a piece whose boundary segments align with:
- a thick line passing from lower-left edge toward upper-right, and
- two thin lines crossing the remaining edges with the same angles.
Step 3: Test the four mini-squares.
Only (C) has the thick diagonal at the correct angle and the thin lines meeting the edges so that, when inserted, all three line paths continue seamlessly across the cut.
Final Answer:
\[
\boxed{\text{C}}
\]