The increased activity of the Underground Railroad in the 1850s suggests that

southern states were becoming more lenient toward runaways.

fewer enslaved people were running away.

there was growing willingness in the North to aid fugitives seeking freedom.

It suggests that many slaves were escaping

Explanation:

the answer B :fewer enslaved people were running away.

the best description of postwar writers might be progressive.

following the war, writers showed a tendency to work on artistic or social matters rather than political themes. while postwar literature may not have been the greatest period of english literature, the themes provided excellent critics a high number of novels. such examples include anthony burgess, anthony powell and frank kermode, all of which can be placed under the progressive view.