Chapter 4: She Must Choose

What?! Mind. Blown.
What I've picked up (I could be wrong) is that every student chooses their Faction, the results of the Aptitude Test are just strong suggestions.

Okay, anyways the choice is Beatrice's, and she must choose between Abnegation and Dauntless. This choice should be her own, but is obviously being influenced by her father's comments about an incident two years prior, where an Abnegation chose to leave for Dauntless.
My mother shakes her head. "That poor man. As if he needs to be reminded of his loss."
"Of his son's betrayal, you mean?" my father says coldly. 
Beatrice, having been raised Abnegation, feels extremely guilty at even the thought of leaving her family for Dauntless, especially after that comment from her father. Based on what her views of her brother are, it seems apparent that he will chose Abnegation as his lifestyle, which also affects her choice.
But she sincerely wants to get out of Abnegation--
"I'm not sure if I can live this life of obligation any longer. I am not good enough."

And just when I think I have Caleb figured out, he says something that makes me question what he will choose.
"Beatrice," he says, looking sternly into my eyes. "We should think of our family." There is an edge to his voice.
Typical Caleb, the selfless, the good child.
"But.
What?! There's a But?!
"...But we must also think of ourselves." 

     I am so startled by his comment that I just say what I am supposed to say: "The tests don't have to change out choices."
     He smiles a little. "Don't they, though?"

Her options: keep living a lifestyle of selflessness, which she's been doing for only sixteen years and is already tired of, or betraying her family to live a new life that she's not even sure she'll like.

"I realize the decision might be simple. It will require a great act of selflessness to choose Abnegation, or a great act of courage to choose Dauntless, and maybe just choosing one over the other will prove I belong. Tomorrow, those two qualities will struggle within me, and only one can win."