Asock drawer contains winter socks and summer socks. both varieties come in two colors: white and black. there is a pair of each combination. if a sock is selected randomly, what is the probability it will be a black sock or a summer sock? a. 0.25 b. 0.5 c. 0.625 d. 0.75

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.