Concept:Terms of trade measures the relationship between a country's export prices and import prices.Explanation:The formula for terms of trade is:Terms of trade=Index of import priceIndex of export price×100Here, the index of export price is 180 and the index of import price is 200.Substitute the values into the formula:200180×100=0.9×100=90Thus, the country's terms of trade is 90.Answer:C. 90.00