Final answer:
The term for fostering separation instead of a cohesive society is segregation, which refers to the physical and social separation of groups and displays the least tolerance among intergroup relations.
Step-by-step explanation:
Fostering separation instead of a cohesive society is called segregation. Segregation refers to the physical and social separation of groups, especially based on characteristics such as race or ethnicity. This can be seen in various aspects of society, including housing, education, and employment. It contrasts with integration, which is the process of intermixing different groups within a society, and assimilation, where a minority group conforms to the dominant society's norms.
Unlike integration or assimilation, segregation often preserves cultural distinctions by preventing close social contact and understanding between different groups. This preservation can occur under both de jure (by law) and de facto (by fact, but not formalized by law) circumstances, as was exemplified by apartheid in South Africa.
The least tolerant intergroup relation based on the available options is segregation, which can perpetuate prejudice and inequality by physically and socially isolating groups from one another.