The Nurse Manager Asks a Staff Nurse Why a Procedure

The nurse manager asks a staff nurse why a procedure is done in a certain manner. The nurse replies, "I don't know why I started doing it this way. I've never read any research on it, but this technique always works for me." The manager would place this technique into which category of evidence?

A) Case study
B) Anecdotal
C) Nonexperimental design research
D) Statistical