Read this line from the Pony Express excerpt:

These resolutions...really foreshadowed the Democratic platform of 1860 which led to the great split in that party, the victory of the Republicans under Lincoln, the subsequent secession of the more radical southern states, and finally the Civil War...

In this context, the phrase "subsequent secession" indicates which of the following?

A. A recent argument

B. A recent confrontation

C. A soon to come declaration

D. A soon to come separation