Which excerpt from "The Roller Coaster" is the best example of external conflict?

Cecelia tapped Teresa on the shoulder. “I don’t like roller coasters,” she said when her friend turned to face her.
Just great, Cecelia thought, I’m going to end up crying and throwing up in front of everyone in school.
Trying to keep up while her friends walked rapidly in the direction of the fun zone, Cecelia criticized herself: Why had she agreed? Why couldn’t she just tell the truth?
As she struggled to reassure herself that she had made the right decision, Cecelia noticed Connor approaching the bench with a bag of popcorn.