TOEFL Reading: ETS-TOEFL阅读机经 - _P8GB196LU14E73HL$

In paragraph 2, the author talks about the "iron nail" in order to A. imply that most products manufactured were considered to be practical or useful B. illustrate that iron was a key player in Britain's economy before the Roman invasion C. give support for the statement that there was much economic activity in Britain following the Roman conquest D. prove that archaeologists have underestimated the degree of the Roman conquest on the British economy