Form Presenter is an add-on for Google Forms that provides additional controls for online assessments.
Form Presenter – Automatic Scoring and Importing to Google Classroom
Three Ways to Allow Retakes of a Google Form
This article covers three ways to offer DELAYED feedback after a form is submitted.
Immediate Feedback in a Google Form using BRANCHING
You can provide immediate feedback in a Google Form using the Branching/Go to Section option to allow students to retry the same question.