The fourth one, voluntary exchange
I believe it is B
Win Shi Huang standardized writing, a crucial factor in the overcoming of cultural barriers between provinces, and unifying the empire. He also standardized systems of currency, weights, and measures, and conducted a census of his people.
I think it can be both B and C
My grandmother shared her wisdom with me when i was young I didn't understand when I was a kid. But as I got older i understood that she experienced these things already and told me from experience. She would say, this too shall pass. I never understood what that meant until I was older. Now I understand that whatever situation I am in good or bad it is only temporary