Which of the Following Was Found to Be True of the Reduction

Which of the following was found to be true of the reduction of hostility at the boys' Summer camp in the Sherif studies?

A) The hostility between the groups was quite weak even at its height.
B) The researchers found it was easy to reduce the hostility once it had occurred.
C) Simply bringing the groups together under pleasant circumstances e.g., a movie showing, a picnic, etc.) reduced hostility.
D) Providing the groups with a cooperative experience in which they had to work together for mutual benefit reduced hostility.
E) Both c and d.