【单选题】About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They requi...
A.
The relationship between a plant's roots and its shoots.
B.
What can be learned by growing roots in isolation.
C.
How plants can be grown without roots.
D.
What elements are necessary for the growth of plants.