Given: ABCD is a trapezoid. Put a checkmark in every box that must be true. You will put more than one checkmark. Use calculations and words to show this quadrilateral meets the definition of a trapezoid.

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.