The correct answer is C) Protective tariffs.
A tariff is a tax on an imported good. This was an integral part of Henry Clay's American System. The American System was focused on developing America into an industrialized nation much like Great Britain. Henry Clay had three key elements of this plan to help America become more industrialized including:
1) A tariff - This would increase prices of foreign goods and protect American businesses.
2) Funds for building infrastructure (i.e. canals, railroads, etc.)
3) A national bank- This would help to foster commerce.