In Sherif's Classic Robber's Cave Experiment, Boys Were Divided into Two

In Sherif's classic Robber's Cave experiment, boys were divided into two groups (the Eagles and the Rattlers) and they began to strongly dislike each other during a series of group competitions. In order to reduce the group tension that had developed between them, Sherif stopped the competitive activities and fostered non-competitive group activities (e.g., watching movies together) . Sherif found that

A) increased contact between the two groups decreased hostility.
B) increased contact between the two groups did not decrease hostility.
C) increased contact between the two groups increased hostility.
D) increased contact between the two groups broke down group tensions.