Some of our customers may want to be able to retake their wrong answers for the Practice Exams, However, our Practice Exams are designed to simulate the actual Salesforce certification exam. In order to give our customers the full experience, we don't give the option to retake wrong answers for the Practice Exams. However, they may review your wrong answers by clicking on "My Past Results" as shown in the screenshot below:
Additionally, If they want to retake their wrong answers, we do offer that for our Topic Exams to help the users prepare and get familiar with the questions. If we may suggest, it is best to finish the Topic Exams first before proceeding to the Practice Exam since the latter is a condensed version of the former.