How has the caste system of south asia changed over the past few decades?

Over the past few decades, the caste system of the south has changed in terms of its marriage in which the marriage in regards with the caste lines are already relatively rare compared before where it is usually practiced or it is something regarded as normal.

the compromise of 1850 was a package of five separate bills passed by the united states congress in september 1850, which defused a four-year political confrontation between slave and free states on the status of territories acquired during the mexican–american war

i believe the answer is d.