An experiment was conducted to determine the effects of fertilizer and bacteria on the growth of clover plants. The experiment consisted of 4 groups. All groups received the following treatments:
Each group then received various other treatments listed below:
The following data were collected (median height of plants measured in centimeters):
|Time after planting||Group A||Group B||Group C||Group D|
Which set of groups should be compared against each other to determine the effect of the bacteria on clover height?