Please Help. Victor made the graph shown to record the observations of an experiment to study the effect of soil additives on the growth of plants. Three identical plants having a height of 25 cm were used for the experiment. The first plant had no soil additives, the second plant had wheat straw in the soil, and the third plant had polymer in the soil. All other growing conditions of the plants were kept constant. (4 points)
(look at image)

Which correct step in the scientific method did Victor most likely do before the step described here?
Analyze the data
Publish the results
Construct a hypothesis
Make conclusions based on the graph