TOEFL Reading: ETS-TOEFL阅读机经 - 59QSY47I06T38EO3L$

According paragraph 1, why does the author mention various agronomical techniques? A. To explain the types of prowess needed to be learned in order for villages to prosper B. To begin a discussion on the relevance of these techniques in increasing productivity of fields C. To isolate the practices that facilitated the increased population size of the villages D. To point out the different jobs that had to be performed on a successful field