The vertices of ΔMNO are M (1, 3), N (4, 9), and O (7, 3). The vertices of ΔPQR are P (3, 0), Q (4, 2), and R (5, 0). Which conclusion is true about the triangles? The ratio of their corresponding sides is 1:2. 
The ratio of their corresponding angles is 1:2. 
They are similar by the definition of similarity in terms of a dilation. 
They are congruent by the definition of congruence in terms of rigid motions.