TOEFL Reading: ETS-TOEFL阅读机经 - M1V574488SDT3LR3L$

According to paragraph 2, why do many seeds require a period of stratification? A. To slowly build up a tolerance for lower and lower temperatures B. To guarantee that the seeds grow after and not before unfavorable weather C. To make sure that the seeds can deal with unpredictable conditions D. To give the seeds enough time to germinate before winter