The angle of elevation of a ladder leaning against a wall is 45°. if the distance from the base of the ladder to the wall is 12 feet, how long is the ladder? select one: a. 8.49 feet b. 16.97 feet c. 15.87 feet d. 29.8 feet

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.