Which of the following inspired a dramatic expansion of support in the north for free blacks and the underground railroad

I believe it would be the industrial revolution and the civil rights movement.

The industrial revolution make companies able to improve their production with more machinaries and less slave labors. Which make the usage of slavery became less and less popular in the north. It also allow the construction of railroad for easier distribution system and The civil right movement bring up equality issues between race majority/minority to the law.