To prevent unauthorized form submissions during the self-registration process, UC should require a captcha at the end of the self-registration process and use hidden fields populated via JavaScript events in the self-registration page. These methods will help to verify that the user is a human and not a bot, and also to validate the user’s input against some predefined values. Option A is not a good choice because open-ended security questions and complex password requirements may frustrate the user and reduce the conversion rate. Option B is not a good choice because lookup and picklist fields may not prevent bots from submitting the form, as they can be easily automated or bypassed.