The correct option is D When a good mix of differences gives rise to a peaceful community.
Cross-cutting differences means that the social groups or individuals having different identities have some similarities as well. It is the opposite of overlapping social differences. A peaceful society exists when multiple identities like language, religion, or economic status are well mixed - it becomes easier to accommodate the differences. It is also difficult to pit one group of people against another when differences are cross-cutting.
One good example is the linguistic social differences in Belgium.