Len notices that the longer he has been friends with someone, the more similar their tastes in movies and clothes become. Which is the best explanation for this positive correlation? Len and his friends have had influences on each other's interests because they have shared many common experiences. By coincidence, Len's long-time friends happen to be around whenever he wants to watch movies or shop for clothes. The moments Len shares with his long-time friends are mostly positive because they rarely fight with each other over outfits or films. A mutual relationship like that shared by Len and his friends is a positive example of how friendships last.