In one study we talked about in class, researchers Webb, Cambell, Schwartz, and Sechrest (2000) wanted to measure patrons' interest in museum exhibits when there were no patrons around to observe. One measure they used was looking at the number of nose- print marks on the glass of certain exhibits, presumably thinking that the more nose-prints, the more interest. Which of the following best describes this research approach? a. Participant Observation
b. Overt Observation
c. Covert Observation
d. Focus Group Observation