TOEFL Listening: TPO-TOEFL听力TPO - I67QR9FVAWXE808FR$

According to the professor, what characteristic of tulips aided the spread of tulip cultivation? A. Tulips grown from seeds produce bulb within a year. B. Tulip bulbs can be removed from the ground and stored. C. Tulips adapt easily to different kinds of soil. D. Tulips are relatively resistant to plant viruses.