From informational reading comprehension the biography of Thurgood Marshall

What is the main idea of the passage?
a. Thurgood Marshall led a successful career as the head lawyer for the NAACP.
b. Thurgood Marshall served as the first African American Supreme Court Justice.
c. Thurgood Marshall achieved many advances for civil rights in the United States.
d. Thurgood Marshall argued and won a landmark case against the University of Maryland.