If a shape in an answer choice is flipped into a mirror image (not just rotated), what does that mean for a fitting-parts problem?

There is an important difference between rotating a shape and flipping it into a mirror image. Rotation turns a shape in place without changing which way it 'faces,' while flipping (reflection) produces a mirror image. For most Assembling Objects fitting problems, a piece shown as a mirror image of the original is a different, incorrect piece — you cannot get a mirror image by rotation alone (think of a left hand versus a right hand). So an answer that requires flipping a piece, when only rotation is allowed, should be eliminated. Recognizing mirror images versus rotations is a key visualization skill on this subtest.