Was it a silly question?

Yesterday, I had to take a placement exam for the diaconate program in our diocese.  (I am considering becoming a permanent deacon.)  Part of the examination process was a series of basic scholastic exams, something between the SAT and the standardized tests my kids take in school.  Part of it, however, was billed as a test of “basic religious knowledge.”   I feel as though I did well on most of it, though I got into trouble on a few of the questions about the 10 commandments, which I was having a hard time identifying by number.  As I told the proctor, I remember what I am not supposed to do, but I can’t remember what order to not do them in!

But one question, however, stuck in my mind because I couldn’t get it.  Roughly paraphrased, it asked:  what is the gift we receive in baptism that allows us to become children of God?  Since it was multiple ch0ice I could eliminate two answers, and was left to dither between two choices:  actual grace  and sanctifying grace.

I confess, I had no clue.  I guessed, and I don’t remember for sure what I guessed—I think “sanctifying grace.”  But this does lead to two questions.

First, can someone briefly define the difference between these?  I looked at the article in the online edition of the Catholic Encyclopedia, but it did not make any sense to me.

Second,  is this a reasonable question to ask on this kind of exam?   I would be surprised if any of the 20+ men taking the test could answer it correctly.  I imagine most of them knew the answer was “grace” but could not draw the fine distinction required to answer the question.  (I am sure that some got it right by guessing between the two options.)  As a teacher, my rule of thumb is to never ask a question that you know that your students won’t be able to answer.   Now this may be sour grapes that I got it wrong; but there were a couple other questions I got wrong (since I had to guess) but in those cases the question itself seemed reasonable:  I felt like I ought to know the answer, even though I did not.  With this question, however, I don’t have that feeling.