A M B H 1 2 3 4 W D E N 5 6 7 8 U 9

As per the given series of letters, which can be classified as:-
Designs 1, 4, 8 ⇒ Consist of three line segments
Designs 2, 5, 7 ⇒ Consist of four line segments.
Designs 3, 6, 9 ⇒ Consist of both straight lines and curved lines.