Theorems about Lines and Angles Practice Test

A student is asked to explain why the SSS congruence criterion follows from rigid motions. The student provides this reasoning: "If two triangles have three pairs of equal sides, then one can be mapped onto the other by a reflection across the perpendicular bisector of one pair of corresponding sides, which preserves all distances." What is the primary flaw in this reasoning?

A geometry teacher asks students to explain why SSA (Side-Side-Angle) is not a valid congruence criterion using the framework of rigid motions. Which student response most accurately explains this using rigid motion principles?