Berkowitz and LePage (1967) found that frustrated men delivered more shocks when:
a. they were initially depressed.
b. badminton racquets happened to be in the room.
c. they had just received a shot that lowered their serotonin levels.
d. guns happened to be in the room.

d. guns happened to be in the room.

Explanation:

The weapon effect theory is a theory of social psychology. It suggests that mere presence of weapon or its picture can lead to aggressive behavior or may produce shock in human participants.

This theory was demonstrated by the Leonard Berkowitz and Anthony LePage in 1967. These researchers selected 100 male university students for one laboratory session.

These were randomly assigned to receive one or seven shocks. These shocks generated by the weapon those were kept on the laboratory and were related to belong to one of the peer. This will may generate mental shock among the students.