You can add feedback to any question created with New Quizzes. Students can view your feedback when they view their results after submitting a quiz. In addition to general feedback, students will see all feedback comments relevant to their answer choices.
You can also add feedback to any answer choice when creating a Multiple Choice question.
Note: Because Essay and File Upload question types require manual grading, any feedback responses added to these question types only display after the quiz is graded and scores are posted.