If a^2-b^2 is to be shown visually, which idea is most suitable?

Correct answer: Remove the smaller b-by-b square from the larger a-by-a square

The direct answer is A: remove the smaller b-by-b square from the larger a-by-a square. A square with side a has area a^2, and a square with side b has area b^2. If the smaller square is cut out of the larger one, the remaining region has area a^2-b^2. This is the most direct visual meaning of subtraction of squares. Option B adds the two areas and therefore represents a^2+b^2, not their difference. Option C describes strips but does not by itself show either square area or their subtraction. Option D shows only an ab rectangle, whose area is ab; it does not represent a^2-b^2. The remaining shape can also be rearranged to demonstrate (a-b)(a+b), but the first visual step is the cut-out. Memory cue: a minus sign in an area model means a region is removed; for a^2-b^2, think of a smaller square cut from a larger square.