Write a story that ends with I had never felt so embarrassed in my life

I remember when I was in my final year in my senior secondary school. I was  the top choice student and naturally was made the school's head boy. Being the head boy almost meant I was invincible to anything in school; or so I thought, until this faithful day.

The cross of being the head boy came with the added weight of the fact that I was expected to lead all the academic extracurricular activities in my school. These activities included external and internal debates, quiz and science competitions. This, ordinarily would have been no problem, save for the fact that I was extremely shy, and very timid- "there is no excuse for failure!" I would always say to myself, and I did quite alright for most of the time, almost always passing the debate to lower class student under the cloak of 'training them.'  

Here comes this big day, and a major debate was set in our school. It was so big that I could not not participate, and the whole school would be in the school hall for the debate. To match what was expected of me, I practiced for two days straight, ahead of the event; practically memorizing everything I had. Hours before the event, I hid myself in an empty class, and practiced more. I concluded I was going to kill it. I though wrong.

The big day came, and my performance was left for last, to be the highlight of the event. When the time finally came, I was already covered in sweat. I couldn't back down now. I thought, and thought, and then summoned enough courage to move my legs unto the stage. The hall went silent with expectation, students, teachers, and guests were all focused on me and I swear I felt their gaze burn through me like laser beams. I opened my mouth to start, fumbled through the greetings and introduction before I realized I had forgotten the topic. I turned around to look at the banner behind me for the topic. When I turned back, my gaze fell straight into the principal's gaze, her face was so serious with the most expectation, and I felt my heart drop. It turned out she was sitting in the first row all these while. I took a deep breath, encouraged myself to say something, and I did- unintelligibly, I had forgotten everything I practiced. Suddenly, the hall started coming alive... with laughter. Everybody was laughing at me, some fell to the ground, others had tears in their eyes. I was the joke of the day. I turned towards the principal, it was like she was laughing the most. My legs shook. I was surprised they still carried me. I looked for the hall's exit and it immediately became very far from me, but I couldn't take it anymore. I made for the exit, through the center of the hall, and the laughter intensified. I made it to the exit and was stuck at the door. I was pulling instead of pushing. It was like the sun should fall on me. After what appeared like minutes, I was able to open the door, and made it outside the hall. I could hear over the public address system the principal trying to calm the hall down in-between her own laughter. I had never felt so embarrassed in my life.

the answer to the question is a