单项选择题

TEXT A
Presiding, like Eisenhower, over a period of relative peace and prosperity at the end of his first term, President Reagan and Vice President George Bush overwhelmingly won reelection in 1984, carrying 49 of 50 states in defeating the Democratic Party ticket of Walter Mondale and Geraldine Ferraro.
Economic trends were by no means uniformly positive in the ’80s, however. By mid-decade, despite robust economic growth, the United States was a nation deeply in debt. Farmers were especially hard hit by depressed commodity prices and loss of export markets, which left them unable to pay off the high-interest loans that they had received in the 1970s, when crop and land prices were high. As a result, the rural economies of many Midwestern farm states were severely depressed.
The farm crisis illustrated another fact about the changing American economy: like most other nations, the United States was increasingly tied to the global economy. Nowhere was this more apparent than in international trade, where the nation registered an ominously large and growing deficit (赤字). In one sense, the imbalance in import over exports marked the success of an open postwar trading system, championed by the U.S., that had progressively lowered tariff (关税) and other trading barriers. American industry, long dominant in the world economy, suddenly found itself in the unaccustomed position of competing for markets, at home and abroad, in basic products such as grain and steel, as well as in advanced technology fields such as electronics and computers. A strong U.S. dollar, which only began to decline in value in the mid-1980s, also contributed to making U.S. exports expensive abroad and imports relatively cheap at home.
A strong American dollar will in a sense affect U.S. international trade because ______.