Which BEST describes a similarity or difference in the authors' purposes?

Responses
A Douglass' passage reveals that his interest in railroads was greater than Grady's interest in railroads.Douglass' passage reveals that his interest in railroads was greater than Grady's interest in railroads.
B Sibley's passage reveals that Grady's interest in railroads was greater than Douglass' interest in railroads.Sibley's passage reveals that Grady's interest in railroads was greater than Douglass' interest in railroads.
C Both passages reveal a great interest in one law, one government, and one administration for men of all races.Both passages reveal a great interest in one law, one government, and one administration for men of all races.
D Both passages reveal a great interest in railroads during the reconstruction of the South after the Civil War.Both passages reveal a great interest in railroads during the reconstruction of the South after the Civil War.

D Both passages reveal a great interest in railroads during the reconstruction of the South after the Civil War.