In this section, you will hear one passage. At the end of the passage, you will hear four questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A), B), C) and D).A、The roots hold onto the soil and keep the tree from falling over.
B、The roots are like the mouth of a tree, which take in water and other materials.
C、Both A and B.
D、Either A or B.