5) Black inventor whose inventions in the 1920's and 1930's improved the heating and air conditioning systems in American homes and businesses.

a. Frederick Jones  b. Otis Boykin  c. Madame C. J. Walker  d. Norbert Rillieux  e. Joseph Lee  f. W. Lincoln Hawkins  g. Lloyd Augustus Hall  h. Garrett Morgan  i. David Crosthwait  j. Elijah McCoy