The Results of the Robbers Cave Experiment Can Be Extrapolated

The results of the Robbers Cave experiment can be extrapolated to suggest that prejudice between groups can be increased under which of the following conditions?

A) when the groups are placed in a situation where they compete against one another
B) when the groups are placed in a situation where appropriate ways of interacting are unclear
C) when the groups are placed in a situation where the groups communicate with one another
D) when the groups are placed in a situation where groups must jointly carry out multiple tasks