Concept:Terms of trade compare export prices with import prices.Explanation:It is measured as the ratio of the price index of exports to the price index of imports.The formula is:Terms of trade=Price index of importsPrice index of exports×100Using symbols:Terms of trade=PmPx×100This shows how much imports can be bought with a given amount of exports.Answer:C. (Price index of export÷Price index of import)×100