Does Atmospheric Pressure Have an Impact on Plant Heights? to Study

Does atmospheric pressure have an impact on plant heights? To study this question, 20 Spartina alterniflora plants were planted at sea level (1 atmosphere) , while another 20 Spartina alterniflora plants were grown in a special chamber aboard the International Space Station (ISS) (0 atmospheres) . The height of the plants after 3 months was recorded. The goal was to see whether the plant heights (in centimeters) were affected by the atmospheric pressure exerted on the plant.
Suppose you make a scatterplot of the data in this study. Which of the following best describes how to format this scatterplot?

A) The amount of atmospheric pressure exerted on the plants should be plotted on the x axis.
B) The amount of atmospheric pressure exerted on the plants should be plotted on the y axis.
C) The plant heights should be plotted on the x axis.
D) It does not matter which variable goes on which axis.