It is often what we think we know already that often prevents us from learning.

    I have been given the challenge to answer many times this question asked by NEC licensing examinees, "Why can't I see the answers that I got wrong?" I can come to only one conclusion, the test question writers strive to make the answers elusive. Very difficult, if not impossible to ever find or know.
    The only time you will ever know the "correct answer" is when you read Tom Henry Books where from all the years of studying the intent of the NEC from the TCD, TCR giving the substantiation for each of the new safety rules or deletions from the NEC each three years.
    At my age 82, I've been through 20 code cycles and written over 90 electrical books which will give you the correct answer in full detail.