The following is an abstract describing the study:

"The participants were 200 men and 200 women (between the ages of approximately 20 and 50) chosen at random while they were walking in a large shopping mall. The participant was tested while walking near areas containing pleasant ambient odors (e.g., bakeries, pastries) or not (e.g., clothing stores). Four young women (median = 20.3 years) and four young men (median = 21.3 years) served as confederates in this study. They were dressed in clothing typically worn by people of this age (jeans/T-shirt/boat shoes). The confederate chose a participant walking in his/her direction while standing in front of a store apparently looking for something in his/her bag. The confederate was carefully instructed to approach men and women walking alone, apparently aged from 20 to 50, and to avoid children, adolescent, and elderly people. The confederate was also instructed to avoid people who stopped near a store. Once a participant was identified, the confederate began walking in the same direction as the participant about three meters ahead. The confederate held a handbag and accidentally lost a glove. The confederate continued, apparently not aware of his/her loss. Two observers placed approximately 50 meters ahead noted the reaction of the passer-by, his/her gender, and estimated, approximately, his/her age. Responses were recorded if the subject warned the confederate within 10 seconds after losing the object. If not, the confederate acted as if he/she was searching for something in his/her hand-bag, looked around in surprise, and returned to pick up the object without looking at the participant."

1. What is the explanatory variable in this study? Select one.

A. Type of ambient scent (bakery, clothing store)

B. Whether or not the participant warned the confederate within 10 seconds

C. Age of the participate

D. Gender of the participant