<p>I don’t know what you mean by “third section,” but generally they won’t let you submit the application without having filled in all required fields. The third essay prompt is completely optional.</p>
<p>If you still have problems, call the number on this website: [University</a> of California - Admissions](<a href=“http://www.universityofcalifornia.edu/admissions/undergrad_adm/apply/afterapply.html]University”>http://www.universityofcalifornia.edu/admissions/undergrad_adm/apply/afterapply.html)</p>