What outside factor most directly contributed to the formation of enclaves in cities?

A: a common culture among American citizens

B:restricted access to education

C:housing discrimination

D: the availability of jobs

Housing discrimination was the outside factor that most directly contributed to the formation of enclaves in cities.

I believe the answer is: C. Housing discrimination

Enclave refers to a part of town which mostly populated by the people from one certain ethnicity/cultural background.

When housing discrimination exist, only people with a certain race or ethnicity are allowed to live on a particular neighborhood. This forced the people from other ethnicities to seek housing elsewhere which lead to the creation of enclaves.