observe the plants and record observations daily move the plants to new locations every day measure the height of each plant every hour add different amounts of water to each plant
I gave my students this multiple choice question: Students wanted to see if the growth of a plant was affected by using four different types of soil. How should the students best carry out this investigation after potting the plants in the four different types of soil?

Only one answer is correct among these 4 choices:
- observe the plants and record observations daily
- move the plants to new locations every day
- measure the height of each plant every hour
- add different amounts of water to each plant

Could you tell me which one is correct?

observe the plants and record observations daily