Which sentence is an example of character vs. self?

Halle did not like Ms. Terry one bit.

The ferocious dog stood between me and the exit.

Yahn's low self-confidence caused him to quit the team.

Richard and Salle just couldn't agree.

The sentence that is an example of character vs. self is the third one - Yahn's low self-confidence caused him to quit the team. You can see that this person was struggling with his own personal feelings that prevented him from staying on the team any longer. The other options are all character vs. character conflicts.