Final answer:
Dr. Martin Luther King Jr. attended both segregated and non-segregated schools throughout his education.
Step-by-step explanation:
The main idea of the passage is that throughout Dr. Martin Luther King Jr.'s education, he attended both segregated and non-segregated schools. The passage highlights how King's high school was segregated, but he excelled academically and graduated three years earlier than most people. He went on to attend a non-segregated college in Atlanta, where his senior class was mostly white and he was elected president. Finally, King obtained a doctorate in theology from a non-segregated school in Boston.