The Harlem Renaissance:
a. describes the quest by writers like Claude McKay to locate the roots of the black experience.
b. marked a turning point in race relations in America.
c. has often been compared to 21st century "gentrification" efforts in the urban Northeast.
d. was a phrase coined by Winston Churchill.

marked a turning point in race relations in America

Explanation:

Harlem Renaissance is defined as artistic,  intellectual, social,  artistic growth which started  in Harlem, Manhattan, New York City, around the year 1920's.   It is also  called the "New Negro Movement".  

loess contribute to the flooding of rivers by providing the silt that is washed into rivers and constantly raises the bed of the rivers. this elevation above the surrounding flood plains and dams allow the river to overwhelm the dams and flood thousand of square miles of neighboring flood plains.

the technology changed agriculture in an impacting manner since many people left the field work by a cellular or other technological appliances