Alisha and her friend have some shapes given below. Alisha thought of the shapes that are similar in a certain way as follows: On what basis did Alisha distinguish the given shapes?

• A.  The shapes are made up of only four sides.
• B.  The shapes are made up of only straight lines.
• C.  The shapes are made up of only curved lines.
• D.  The shapes are made up of more than four sides.