Why might control of the heartland be less important today than it was in world war ii?

Plz which of the following provisions of the compromise of 1850 was designed to appeal to slave states? a. congress passed a strict fugitive slave law. b. the slave trade was banned in washington dc. c. texas agreed to give away some of its land so that the territory would be available for future states. d. california was admitted to the union as a free state.