Which historical fact will best readers understand this excerpt?

the folly of men has enhanced the value of gold and silver because of their scarcity; whereas, on the contrary, it is their opinion that nature, as an indulgent parent, has freely given us all the best things in great abundance, such as water and earth, but has laid up and hid from us the things that are vain and useless.

a) explorers during this period went to the new world in search of scarce resources.

b) during this period, the king was fighting for power that was held by church leaders.

c) many people were dying from the black death during this period.

d) increased prosperity during this period allowed more citizens to buy land.