Cynthia is making peanut butter cookies. Her recipe calls for 2 cup of peanut butter to make 1 dozen cookies. Which fraction best represents the ratio of cups of peanut butter to number of cookies? A 1/36 B. 1/12 C 1/6 D 1/4

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.