Your Study Partner Can't Understand Why Professor Shultz Spent So

Your study partner can't understand why Professor Shultz spent so much time discussing z scores, in that they don't seem all that important. What would be your response to your study partner as to why z scores are so important in the field of tests and measurement?

A) They allow for both positive and negative scores.
B) They are easily understood by non-testing professionals.
C) They allow comparisons across different distributions of scores.
D) They always carry a positive connotation regarding test performance.