Answer
The variable trends are observed in the graph depicting the average level of happiness at different times of the day for women.
Work Step by Step
From the above graph, at 8 a.m. in the morning on an average a woman’s level of happiness is least and by 9 a.m. it increases slightly.
So, in the next 1 hour, a decrease is observed. But, soon after that, on average, the happiness level is found to be 3 by 12 noon.
We see in the graph that the happiness level fluctuates about 1.5 by 3 p.m. (15 hours). After a slight decrease for the next 1 hour, the happiness level shows a progressive increase up to a maximum of about 4.5 until 11p.m. (23 hours).
Also, it can be noticed that until 19 hours (7 p.m.) the graph would be a one-to-many function as the happiness levels are the same for 2 different time instances. But, after 7 p.m., a constant rise is observed and the horizontal line will intersect the graph at not more than one point and hence this shows one-to-one behavior.