Recall That Researchers (Pennebaker & Sanders, 1976) Placed One of Two

Recall that researchers (Pennebaker & Sanders, 1976) placed one of two signs in the bathrooms on a college campus. One was a strong warning ("Do not write on these walls under any circumstances") and the other was a milder admonition ("Please don't write on these walls") . Two weeks later, what were they likely to find in the bathrooms containing the strong warnings?

A) Scrawls that read, "Says who?" and "What are you going to do about this?"
B) Graffiti in the stalls but not on the walls, where the sign was posted
C) Walls that were relatively clean
D) Less graffiti, but signs posted everywhere