Currently we can "allow multiple attempts" and "show correct answers at," the only thing that is missing is showing the correct answer comments when the correct answer is displayed. Simple example:
What is 2 + (-2) ?
A) 4 (Comment: this is the answer for 2 + 2)
B) 0 (Comment: that’s correct, start at 2 and subtract 2 leaving you with 0)
C) 2 (Comment: you start with 2, the other portion of the equation isn’t 0, your answer won’t be the same)
Let's say the students get 2 attempts, other settings dictate that the correct answers will be shown after the final attempts. If the student answers incorrectly in their 2 attempts they will then be shown the correct answer is 2 but the comment or explanation is not included. This doesn't allow them to learn why it is incorrect.