According to the Plurality Opinion of the Supreme Court in U.S.v.Mendenhall

According to the plurality opinion of the Supreme Court in U.S.v.Mendenhall involving an airport investigation of possible drug law violations:

A) voluntary cooperation is determined by whether the agents actually tell citizens they are free to leave.
B) seizure is determined by whether reasonable persons,under the circumstances,would feel or honestly believe they are not free to go.
C) a person is seized whenever they are moved from the place where the encounter with the police occurs.
D) a person is not seized unless the officer tells the person he or she has been arrested.