During a Break from Working on a Task, a Research

During a break from working on a task, a research participant (Regan, 1971) received a soda from the confederate who was partnered with them. At the end of the day, the confederate asked the research participant to buy lottery tickets and those who earlier had received a soda, were more likely to buy tickets; demonstrating the ideas behind the norm of

A) reciprocity.
B) assertion.
C) reaction.
D) social responsibility.