I believe the answer to that would be "B", "descriptive, yet brief."
Answer:
9=a 10=c 11= d 12=a 13=b 14=d 15=a 16=c 17=a 18=b
Explanation:
You can use the (Unique) constraint to compare one column against another column. Hope I got it right.
Some do not pay attention to things like that.
