Andrea Is Studying the Conditions Under Which People Become Attracted

Andrea is studying the conditions under which people become attracted to each other. She invites male research participants to visit the lab and interact briefly with an attractive person (a paid research assistant) . By flipping a coin, she places participants in one of two conditions: 1) The conversation occurs without incident, or 2) There is a brief blackout in the research lab during the conversation. At the end of each session, the attractive research assistant gives the research participant her home phone number and invites him to call her later. In this study, whether the research participant calls the number is the:

A) operationalization of the dependent variable.
B) operationalization of the independent variable.
C) control variable.
D) predictor variable.