Answer:
B. Busing
Step-by-step explanation:
Busing most raised racial tensions in Northern cities.
Busing was a federal policy aimed at integrating public schools by transporting students from predominantly minority neighborhoods to predominantly white schools, and vice versa. This policy was implemented in the late 1960s and early 1970s and caused controversy and opposition from white residents in Northern cities who felt that their neighborhoods and schools were being disrupted. This opposition led to racial tensions and conflict.
A, C, and D all refer to segregation policies that were prevalent in the South, not in the North.