While attending a concert, Brian hears a loud explosion in the crowd. Seeing that the majority of the concertgoers run in one direction, Brian believes that people are running to that direction for a good reason and conforms by running in the same direction. Brian's reaction is based on

Answer: Informational influence

Explanation: People tend to exhibit informational social influence when they conform or follow the path or direction in which the large majority of members of a group are headed. This tendency is also called social proof whereby one psychologically believes that the decision or direction taken bay the majority is good or probably the best to follow. This can be related to Brian's situation in the context above, whereby he followed the direction of the crowd because he believes that for a large proportion of the attendees to move in that direction, it probably should be the best direction to follow.