test prep funny...

I was working a small group of 4th graders after school helping them get ready for upcoming standardized testing. We came across this question, that ended in a ball of laughter. The correct answer "should" be (D) dull, however, most of the kids chose (A) dirty. Since they are both grammatically correct, I really couldn't argue that they were wrong. I can only imagine what the creators of this particular worksheet were doing while making it!