Testing information retention is fine.
But the information "The textbook claims A is the correct answer" is not worth remembering, is it?
For example, I've read Code Complete 2, and while browsing online I found that some of the claims in the book was not solid.
- https://www.sicpers.info/2012/09/an-apology-to-readers-of-te...
- https://www.lesswrong.com/posts/4ACmfJkXQxkYacdLt/diseased-d...
The point made in the above links are interesting but, because I remember reading this particular book, they are sticking more deeply in me.
Also it probably depends heavily on the topic.
For example in economic or philosophy, there are different schools of thoughts and I think it is valuable to know from which school a "fact" is attached to. And before learning about every school, it is probably easier to just remember where you first read it.
This is not critical, but maybe having this information can help you create new insights.
On the other hand, these tests are usually meant to evaluate learning progress and are not themselves thought of as teaching material. I find this quite unfortunate and would really wish that an exam were more like an individual learning session but here we are.
Thus, while this question as it it might advance understanding, it might at the same time hinder progress because someone will fail the exam for giving the wrong answer.
Or for spending too much time on a question that someone who failed to get the lesson answered in a second. This is an answer to what if the question is not meant to be answered "correctly" but just to stimulate learning. Unless the whole exam does not get graded - which would be great and hilarious at the same time - I fail to see the fairness here.