Thanks Yang and mpp2016! Your comments were useful. I actually managed to find a good subject to talk about and it turned out quite well.
I have another question, this time about the optional essay. Unlike spring 2016 essays, this time there's no word limit for the optional essay. Now, having already written a few essays to other schools, I have an essay of about 700 words that fits well with the optional essay's directions and is ready to go. However, I am reluctant as to submitting such a long essay, given that the word limit for the spring optional essay was 300 words.
What do you say? I'm actually looking for somebody to tell me I'm overthinking it, and that 700 words when no word limit is mentioned is just fine