Step 1: Understand what generating the figure means. The top strip is built by taking one small square tile, a fixed arrangement of black and white unit cells, and repeating it side by side until it fills the long horizontal band shown in the question. Only one of the four labelled tiles, P, Q, R, or S, reproduces this band exactly when repeated.
Step 2: Fix a reference block in the strip. Pick one clearly bounded block from the left end of the strip, matching the width of the square tiles P, Q, R, S. This block is the actual repeating unit used to build the whole strip, so it must be identical, cell for cell, to the correct tile.
Step 3: Compare each candidate tile to the reference block. Check each tile's black and white cell pattern square by square against the reference block taken from the strip. Tiles P, R, and S each match the reference block in their overall outline but differ from it in at least one small cluster of cells, a black cell appears where the strip has white, or vice versa, in one corner or edge region, so repeating any of them would create a visible mismatch somewhere along the strip. Tile Q matches the reference block cell for cell with no discrepancy anywhere in the tile.
Step 4: Confirm by checking a second block further along the strip. Take another block from further right in the strip and repeat the comparison. Tile Q again matches exactly, confirming that Q is the tile that, when repeated, produces the entire strip shown, not just one section of it.
Step 5: Why the other options are wrong. Option (A), P, has a small cell-level mismatch against the reference block, so tiling it would not reproduce the exact strip. Option (C), R, likewise fails cell-by-cell comparison at a different spot in the tile. Option (D), S, also has a mismatched region when checked against the strip. All three look superficially similar to the correct tile at a glance, which is exactly why the question needs a careful cell-by-cell check rather than a quick visual impression.
Final Answer: The pattern labelled Q is the one used to generate the figure.
