in the direction of moisture only in the direction of the pull of gravity only in the direction of water and the pull of gravity in the direction of water and away from the pull of gravity
I gave my students this multiple choice question: In which direction do the roots of plants grow?

Only one answer is correct among these 4 choices:
- in the direction of moisture only
- in the direction of the pull of gravity only
- in the direction of water and the pull of gravity
- in the direction of water and away from the pull of gravity

Could you tell me which one is correct?

in the direction of water and the pull of gravity