Which of the following could best be used as evidence to support the argument in the excerpt that "ethnic conflict among whites rivaled sectional conflict as a major political issue" of the period?
A) A series of racially motivated riots in urban areas during the time period.
B) Statistical data showcasing the rise of racially charged political parties and movements.
C) Analysis of newspaper articles highlighting the intensification of ethnic tensions in various regions.
D) Correspondence between political leaders discussing strategies to address rising ethnic tensions within the country.