the final sentence in this chapter in which the factionless man warns Beatrice Choose Wisely little girl is an example of​

Foreshadowing.

Explanation:

Foreshadowing is the literary device used to talk about something that is bound to happen in the coming future. It is used to talk of possible hints about what might happen in the story.

In Chapter 3 of the book "Divergent" by Veronica Roth, Beatrice "Tris" Prior is seen walking home after the "test" to determine what will be their choice. And in this test to determine whether the person will be an Erudite, Amity, Dauntless, Abnegation, Candor, Tris's result turned up to be inconclusive. And on the walk home, she helped a "factionless" man, giving him food. But then the man, after learning that she's got to choose her side the next day, warns her "choose wisely, little girl." This warning foreshadows the 'dilemma' in Tris about which section she will choose, or be most capable of belonging.