B and C
Combine your ideas. C is great but not 100% clear.
Riding a roller coaster to overcome my fear of heights showed me that I was brave and able to tackle any obstacle ahead of me.
A personal narrative should be written to show how the author has grown or changed because of an experience. The thesis statement needs to show this growth. The first option is not correct, because thesis statement only tells he has a fear or heights and he rode a roller coaster. It does not indicate what the author learned. Option C and D both say that the author changed or learned something, but it's not specific enough. Option B is the only option that shows how riding the roller coaster changed the author.
The best personal narrative about Paolo’s experience to overcome his fear of heights by riding the roller coaster is “Riding a roller coaster to overcome my fear of heights showed me that I was brave and able to tackle any obstacle ahead of me.” Personal narrative shows a story of one’s life by telling your experiences.