Which statement correctly describes the relationship between △def and △d′e′f′ ? △def is congruent to △d′e′f′ because you can map △def to △d′e′f′ using a reflection across the x-axis, which is a rigid motion. △def is congruent to △d′e′f′ because you can map △def to △d′e′f′ using a reflection across the y-axis, which is a rigid motion. △def is congruent to △d′e′f′ because you can map △def to △d′e′f′ using a rotation of 180° about the origin, which is a rigid motion. △def is not congruent to △d′e′f′ because there is no sequence of rigid motions that maps △def to △d′e′f′.