Answer Key and Points
Screenshot of the Answer Key option page allowing quiz builder to choose correct answer and assign point valueScreenshot by R. Krantz

If your form is already set up as a quiz, you will have an "Answer Key" option in the bottom left of the question box (when you click it, it will change to "Edit Question").  

After you have filled out the multiple choice options, select the "Answer Key" option and choose the correct answer. This is also a good time to add a point value to your question.

Google Forms will use the answer you selected to create a key and automatically assign points to students for correct answers. Students will receive immediate feedback and the assessment will be done in a flash, giving you immediate access to helpful data!