Concept:The terms of trade compares a country's export prices with its import prices.Explanation:It is measured as the ratio of the index of export prices to the index of import prices.The formula is:Terms of Trade=Index of Import PricesIndex of Export Prices×100This ratio helps determine whether a country earns more from its exports than it spends on its imports.Among the given choices, this ratio is known as the terms of trade.Answer:C. terms of trade