The answer is D: still exists today.
Explanation for each option:
a) Was struck down by Brown v. Board of Education: This is incorrect. Brown v. Board of Education (1954) was a landmark Supreme Court case that declared state laws establishing separate public schools for black and white students to be unconstitutional. It specifically addressed de jure segregation (segregation by law), not de facto segregation (segregation in practice).
b) Was banned by the 1964 Civil Rights Act: This is incorrect. The Civil Rights Act of 1964 outlawed discrimination based on race, color, religion, sex, or national origin and ended unequal application of voter registration requirements and racial segregation in schools, at the workplace, and by facilities that served the general public. However, it did not address de facto segregation, which occurs through social, economic, and other factors rather than legal mandates.
c) Was defeated by Dr. King and the civil rights movement: This is incorrect. While Dr. Martin Luther King Jr. and the civil rights movement made significant strides in combating racial discrimination and segregation, de facto segregation still persists in various forms, such as residential segregation and disparities in education and employment.
d) Still exists today: This is correct. De facto segregation refers to segregation that occurs in practice, even if not enforced by law. It still exists today in various forms, such as in housing patterns, school demographics, and economic inequalities.