Classify each of the following transactions as belonging pn'marily t0 the sphere of international trade analysis (T) or international monetary analysis (M). {Enter Tfor Trade or M for Monetary) Primary Sphere Transaction (T.trade, Mmonetary} Foreigners purchase U.S. dollars. The U.S. imports crude oil from the Middle East. The U.S. imposes tariffs on foreign steel. The Chinese government purchases US. treasury bonds. The Chinese currency is seen as being undervalued. Economists use the term opportunity cost to refer to O A. only those goods which are in short supply. 0 B. the value of all alternatives forgone as a result of making a particular choice. 0 C. the value of the next best alternative occurring as a result of making a particular choice. O D. either 3 or C