Meiko is hanging a picture-collage on her wall. It is in the shape of a parallelogram. How much wall area will it cover? A parallelogram has a base of 18 inches and a height of 28 inches. A. 156 in.2
B. 252 in.2
C. 504 in.2
D. 576 in.2

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.