TOEFL Reading: ETS-TOEFL阅读机经 - XVF6MIX6NXBFZDQJL$

According to paragraph 1, why did North American colonists trade with their neighbors? A. They preferred not to accept cash for goods they had to trade. B. They were not able to produce everything that they needed. C. They had difficulty establishing book credit with the local storekeepers. D. They wanted to balance the credits and debts in their account books.