Can some one explain please

Name the most appropriate metric unit for each measurement like a length of an carrot

Askate shop rents roller skates as shown on the table below. which graph and function models this situation?

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.