Hard rock mines were operated by mining

a. lumber companies
b. trusts
c. chinese immigrants
d. corporations

d. corporation

Explanation:

lumber companies chopped down trees and processed them into planks

Chinese immigrants might work in the mines but they didn't operate them

Trusts: a trust is a three-party fiduciary relationship in which the first party, the trustor or settlor, transfers ("settles") a property (often but not necessarily a sum of money) upon the second party (the trustee) for the benefit of the third party, the beneficiary.[1]

it would be that mali has the worst literacy rate than the others

although the crusades failed to capture jerusalem, they had several major impacts on western europe. they increased the authority of the king: sometimes nobles died in battle without leaving an heir in which case the king got their land. kings passed taxes to pay for the crusades.