How we cite our quotes:
"I don't think I have any choice but to kill him now," [Edward] muttered. (19.85)
Edward speaks of the tracker, James. If James isn't killed, he'll hunt Bella forever.
Carlisle looked gravely at Laurent. "I'm afraid you're going to have to make a choice." (19.110)
In Carlisle's mind, Laurent is either with the Cullens or against them.
I pushed the terror back as well as I could. My decision was made. It did no good to waste time agonizing over the outcome. I had to think clearly, because Alice and Jasper were waiting for me, and evading them was absolutely essential, and absolutely impossible. (21.76)
Bella sees no range of possibilities. Either she attempts to save her family, or she runs away and risks them getting hurt. Because she values her family so highly, she chooses to sacrifice herself.