The answer to this is unclear. Technically you do not need to answer this question. Applicants receive interviews without filling it out. Nonetheless, the optional section is a good opportunity to write a unique essay that might help the admissions committee get to know you better. Here are some potential topics:
- Write about an important activity you recently started.
- If the application does not have a “why X school section”, write why you want to attend the school.
- If you had a difficult life circumstance that impacted your grades, you can describe it here.
- If the application does not have a “what makes you unique” section, you can write about that here.