When Congress passed the Underwood Tariff Bill in 1913, it intended the legislation to a eliminate tariffs as a source of revenue b decrease tariff rates c increase tariff rates d aid American farmers

b. decrease tariff rates

Explanation:

The Underwood Tariff Bill in 1913, as known as Revenue Act of 1913, was implemented during the administration of President Woodrow Wilson. This bill focused on making the revenue system efficient as a part of the Progressive Movement reforms.

The Progressive Movement was a reformist movement where different ideas and reformist activities were emphasized between 1890s to 1929s. It aimed at bringing reforms in the social, economic and political aspects of the country.

The Underwood Tariff Bill in 1913 was passed to reduce tariff rates on foreign goods so that the price of imported foreign goods and services would lower down which would also ultimately lower the living cost of the Americans as prices of goods and services will be affordable for all.