As a child, Dr. Martin Luther King Jr. attended segregated public schools. The law said that black students like King had to go to their own schools, separate from white students. King was a good student, and he graduated high school three years earlier than most people do. He went to college in Atlanta, Georgia. King then went on to study theology, the study of religious faith, at a school in Pennsylvania. This school was not segregated. In fact, King's senior class was mostly white, and he was elected president of it. King's education wasn't finished yet. In 1953, he got yet another degree from a school in Boston: a doctorate in theology. A doctorate is the highest degree that universities give out. This is why King is called "Dr. Martin Luther King Jr." What is the main idea of the passage?

A
King graduated high school earlier than most people do.

B
The school in Pennsylvania where King studied theology was not segregated.

C
King was elected president of his mostly white senior class.

D
Throughout his life, King was educated at many schools, some of which were segregated.