Aretha is correct. Since a rhombus a is a quadrilateral with 4 equal sides in terms of length, (forming 4 right angles in each corner), it can be concluded that all squares are rhombuses. However, only some and not all rhombuses are squares because some rhombuses may have equal lengths but all corners don't form right angles.
All squares are rhombuses because, by definition, a rhombus is just any parallelogram with four equal sides. However, not all rhombuses are squares, because a square must have four equal sides with all right angles.
