All of the flowers now raised here have deyeloped from those ____in the forest.(为什么)

问题描述:

All of the flowers now raised here have deyeloped from those ____in the forest.(为什么)
a\once they grew b\they grew once c\that once grew d\ once grew

C 定语从句.that作主语.那些曾经生长在森林的花.