Which of these best describes the central theme of the passage?
a) Explaining how each of these pioneers excelled in their fields and went abroad
to obtain higher degrees to boost their careers
b) emphasizing how each of these pioneers overcame obstacles and adversities
to bring about positive changes for the country and the world, and thus
deserves recognition and a place in the history
c) sympathizing with these lesser-known African-American pioneers whose great
efforts went in vain
d) drawing attention to the sufferings of African-American people in the country
and the severity of discrimination and inequality they had to deal with