Although the Groups in Schachter and Singer's Study Were Exposed

Although the groups in Schachter and Singer's study were exposed to the same angry confederate, one group reported more subsequent feelings of anger than the other. Why?

A) The angrier group had been injected with adrenaline.
B) The angrier group had to wait longer in the confederate's company.
C) The angrier group was not informed about the physical effects of the drug they were given.
D) The angrier group had been led to expect that they would become angry.