Is there a way learners can see the reasoning for why an answer to an assessment is correct or not?

Hey ​@DHerbert 

It sounds like what you are asking about are answer rejoinders. Here is a support article about this feature:https://support.thoughtindustries.com/hc/en-us/articles/360045729694-Creating-a-Quiz-Page

I’ve created a couple of screenshots to explain what this looks like in your instance: 
 

Display correct answers prior to question completion after certain # of attempts: Rejoinders are shown for the correct answers after a learner exhausts all allowable attempts so learners can review answers and rejoinders.

Only correct answers in review after a learner passes the assessment: This setting is shown when "Display correct answers prior to question completion after certain # of attempts" is enabled. Learners will only see correct answers after they pass the quiz.

Let us know if this is what you’re looking for. If not, please share additional context. 
Many thanks and Happy Learning!
Jeanne from Success Team