TOEFL Reading: ETS-TOEFL阅读机经 - 1LR34A5QD21PG8U3L$

According to paragraph 1, all of the following have been proposed as the primary cause of the development of subsistence strategies that involved domestication EXCEPT: A. growing population pressure on existing food sources B. the drying of the climate C. the movement of human populations to new parts of the world D. famine