In a tile model, one x² tile, four x tiles, and four unit tiles form which square?

Correct answer: (x+2)²

The correct answer is A: (x+2)². One x² tile represents an x-by-x square. Four x tiles can be arranged as two rectangular strips, each with area 2x, and four unit tiles form a 2-by-2 corner square with area 4. These pieces fit together to make a larger square whose side is x+2. Algebraically, (x+2)²=x²+2(x)(2)+2²=x²+4x+4, exactly matching one x² tile, four x tiles, and four unit tiles. Option B would require eight x tiles and sixteen unit tiles because (x+4)²=x²+8x+16. Option C is not the correct expansion and does not show a square form. Option D would involve negative strips and is unsuitable for this positive tile arrangement. Memory cue: four unit tiles make a 2-by-2 corner, so the added side length is 2, not 4.