Three coins are tossed at once. What is the probability of two heads and one tail?

Which of these tables represents a non-linear function?

Ineed to know the answer to this algebra question.

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.